tag:blogger.com,1999:blog-20310719431789785562019-08-05T11:54:32.223+01:00 detuned radioUnknownnoreply@blogger.comBlogger386125tag:blogger.com,1999:blog-2031071943178978556.post-72524224785552470962018-01-23T22:39:00.003+00:002018-01-23T22:40:18.985+00:00The Art of Puzzles: SlitherlinkA quick heads up - I have a slitherlink puzzle published on Grandmaster Puzzles today! See <a href="https://www.gmpuzzles.com/blog/2018/01/slitherlink-tom-collyer/">https://www.gmpuzzles.com/blog/2018/01/slitherlink-tom-collyer/</a> for more details.Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-2031071943178978556.post-51220808559137414092017-09-24T23:03:00.001+01:002017-09-25T20:36:43.292+01:00Times Sudoku Championship 2017So I suppose I had better write something about winning this year's competition before an article appears in tomorrow's paper if 2015 was anything to go by - although the fact that it wasn't a snotty work experience boy who did the interview this year, and I haven't been woken by a desperate phone call asking "is there anything interesting about you?" I suppose is a good sign.<br /><br />In previous years I have had to get up very early on a Saturday morning to make it in time for the competition, which takes place at the News building opposite the Shard . This year is much better as I have recently moved to London and find myself living about a 10 minute walk away.<br /><a name='more'></a><br />This year I had put in a fair amount of practice before the competition, mainly in the form of the freebee "The Times Fiendish Su Doku Book 9" they handed out last year. Working my way through this led me to the conclusion that the current Times definition of Fiendish is a little loose - I suspect there might be 2 or 3 different things which might ultimately push a puzzle into its fiendish bracket. This was not particularly reassuring, as it doesn't offer too many clues about what kind of technique might unpick a sticking point. If you end up looking for the wrong thing then I know exactly what happens: in the final of the 2016 competition I was left utterly flummoxed and held everyone up (and still only had 3/4 correct), leaving me to claim a rather sobering 7th place.<br /><br />Perhaps it was just the morning start or a general lack of sharpness, but the first round of 4 puzzles seemed to back this up. I solved these very nervously, and had to make a couple of guesses to get them all out in approximately 30 minutes. I think this was the 4th fastest with all correct - although I also believe that WSC team mate Heather Golding and 2013 champion Stephen Gerrard might both have been faster as well. They both ended up with small errors, effectively ruling them out of the grand final. This does feel a bit harsh, and I can definitely sympathise with them having done something similar in 2008, 2010 and 2012. However, them's the rules, and since 2014 (I didn't participate in 2013) I haven't made an error that I wasn't subsequently conscious of before handing in so hopefully weeding them out is something that can be learned. Winner of this round was a new name to me, Madeleine Jacob.<br /><br />Anyhow, my 30 minute performance was quite demoralising; and although it was backed up by the general feeling in the room that this set was quite hard (to put this into perspective I have since given this round to one of the best solvers in the world, Chinese champion Tantan Dai, who finished it in 14 minutes) it wasn't hard enough to really have warranted guessing in two of the puzzles. What I found really helpful this year was in the break between the first and second round, whilst sitting down with Heather and another WSC team mate, Mark Goodliffe, I went back over and solved both the puzzles that had caused me grief in a fully deductive manner.<br /><br />I think this set me up nicely for the 2nd set, which I got through OK in about 20 minutes, which is much more like it, albeit still with the feeling that I was a little slow to spot things. Perhaps this has something to do with the grids being a little bigger than normal. In previous years I'm sure I've said that I prefer this because it makes spotting x-wings and swordfish a little easier. Maybe I'd still hold that opinion if these puzzles required those harder techniques, but under the current supplier (Puzzler Media) they do not, and the fact of the matter is I much prefer being able to take in the whole grid at once now. Perhaps another theory is that the bigger grids involving more hand movement and/or having to write slightly bigger, all of which might add up when drawing in 50+ characters into the grid - it's a theory I wouldn't pay too much attention to, having conducted the interesting experiment of handing the 2016 grand final puzzles to the the 2016 world champion, Tiit Vunk, and sat down next to him to watch him solve on an original copy of the over-sized puzzles. He wolfed them down in (I think) 11 or 12 minutes. <br /><br />But I digress. I was fairly confident I was fastest in the room so felt l could definitely spare a few minutes to check a little more thoroughly than I usually do, and as I was doing so, Nina Rowe handed in to win Round 2. This prompted me to do what I always do when I'm checking a little more thoroughly: conclude I wasn't actually getting any value out of it, and instead handed in to claim 2nd place for the round. This in itself felt a little strange, as I think I normally win at least one of the preliminary rounds most years.<br /><br />In an interesting twist this year, there were 12 grand finalists this year, which was good news for defending champion George Danker, who had had his moment of freezing up in the the 2nd round, apparently taking 35 minutes to solve one of the puzzles. Luckily enough, the remaining 3 took him about 10 minutes, which still had him way down the rankings for this round, but the combined rank with the 1st round was enough to see him through in 12th place. Whilst Heather and Stephen may have been holding out for a few mistakes, this year the number of 8/8 solvers was 15, so neither was able to make the final.<br /><br />For the final itself I was still a little unsure about how well I was solving, although I had clearly improved between Round 1 and Round 2. It felt to me that the favourite was going to be Nina Rowe, who had qualified very strongly in 2nd and 1st place - however the field also included previous champions George and Mark as well as a few other grand final regulars and some newer names who unfortunately I didn't have any time to meet or talk to. With such a wide list of potential winners, this format always feels a little bit of a lottery to me. I'm quite confident of my solving speed and would usually make myself the favourite, however I never quite feel like my chance of winning having made the final is more than 20-30% - and I'm sure other finalists must feel their chances aren't too far behind this. The stats show that my record in grand finals is now 4 wins from 8 (7 if you exclude the 1v1 knockout format used in 2006) so make of that what you will.<br /><br />I suppose the nerves get to people in this final, because it became apparent very quickly that Nina was doing a serious amount of rubbing out. On the other hand, I was making very good progress over the first couple of puzzles I tried, and when I looked up after finishing the second I had used up about 9 minutes. Still wary that I might come grinding to a halt, my pulse raised a bit as I got through the 3rd, and by the time I was halfway through the 4th I knew I was on to something good. If anything, I felt like I had been slightly slow to spot a couple of things in much the same way as I had in the 2nd round, but it was still pretty good, as after a quick check for empty cells I handed in with 16 minutes gone. I knew I had solved pretty damn well and gave a fist pump. Apparently David Parfitt, the puzzle editor of The Times, who was running the show at the front of the room was worried he'd let out an audible "wow!" (I didn't hear this), but this was probably justified given that 2nd place, Madeleine, handed in about 10 minutes later. <br /><br />She was shortly joined by Ned Walker in 3rd place, rounding off the podium, although I wasn't paying too much attention, because as in previous years I had to sit and wait in silence for everyone to finish and to confirm I didn't have a mistake. This year I made use of the freebee book, "The Times Ultimate Killer Su Doku Book 9", which apparently features "Extra Deadly" rated puzzles to keep me distracted, and I managed to finish off two suitably challenging puzzles within the remaining time.<br /><br />After everyone had finished, it emerged that rather remarkably there weren't any mistakes in the final - perhaps this had something to do the £200 2nd place prize and £100 3rd place prize. I was very satisfied with my performance, and was glad to be holding the trophy again - although I suspect the photo in the paper tomorrow isn't going to be entirely flattering given the daze I was in at the time. However, the day ended nicely enough with me spending the first of the £1,000 prize money buying whoever was left around a drink at the bar in the Shard. Here's hoping I can have a decent shot at the title next year too!Unknownnoreply@blogger.com2tag:blogger.com,1999:blog-2031071943178978556.post-34446189663081300222017-07-08T18:45:00.000+01:002017-07-08T18:47:10.668+01:002017 Sudoku GP: Round 7 RussiaSo this was a round that I really wanted to finish to cement a good end to the GP series. the puzzles this time round were provided by Andrey Bogdanov of Russia, a stalwart puzzle writer who also writes some interesting, if rather difficult sudoku variations as well.<br /><br /><b>Enjoyment:</b> 6/10<br /><b>Classics: </b>6/10<br /><b>Favourite Puzzle:</b> Killer Sudoku<br /><br />The theme for this round was Tetrominoes, of which there are 5: L, I, T, S and O.<br /><br /><a name='more'></a><b>1-5 Classic Sudoku (12, 13, 19, 21, 28 points)</b><br />Nice enough classics, although the first two cannot possibly be scored consistently with the classics in the rest of the competition. I am inclined to believe that the test probably had one too many puzzles. I only got around to two of these during time, with a silly mistake in the 13 point puzzle.<br /><br /><b>6 Letter Sudoku (47 points)</b><br />Just a classic, but using the letters TOMSLINER. The unfamiliarity with the symbols always makes these a little slower, but I think this was genuinely quite a hard classic. I would have preferred to have had this as a 1-9 classic and then swapped in one of the previous classics to have as the Letter puzzle. On the other hand the letters did have a tetromino theme. It feels like givens at R6C6 and R6C7 were omitted in error given the otherwise symmetrical positioning of the givens.<br /><br /><b>7 Nonconsecutive Sudoku (71 points)</b><br />This was hard, and I had to guess a lot. On the other hand, you could solve this very quickly with a punt if you noticed that in all 9 rows and columns you had sets of repeating triplets. It's definitely worth noting that repeating triplets is definitely a theme within all <i>non-consecutive</i> puzzles, however this punt on both rows and columns is far from guaranteed - there was a filthily difficult <i>non-consecutive</i> sudoku puzzle in the 24h Puzzle Championship earlier in 2017 which did not conform to this pleasing regularity. Givens as tetrominoes.<br /><br /><b>8 Cloned Shapes Sudoku (29 points)</b><br />Or Clone Sudoku as it is better known as. I didn't have time for this during the test. The tetromino theme continued as the cloned areas.<br /><br /><b>9 No Touch Sudoku (76 points)</b><br />I thought this was over-valued. Sure it was difficult, but there were 50 point puzzles on this puzzle that both felt harder and took longer to solve. Maybe I'm just reasonably good at this type.<br /><br /><b>10 Odd Sudoku (18 points)</b><br />Pleasant enough. More shaded tetromino areas.<br /><br /><b>11 Renban Sudoku (28 points)</b><br />Again, I prefer Renban Groups Sudoku. Again, pleasant enough. Again, shaded tetromino areas. Also worth noting I got the answer keys out having solved only 2/3 of the puzzle.<br /><br /><b>12 Antiknight Sudoku (64 points)</b><br />Well, this is at least better than Antikinght Sudoku from Round 6, but a hyphen would be nice. Not a type I'm good at, and combined with this not being particularly easy probably meant I really suffered on the points per minute ratio for this puzzle. Givens as tetrominoes here.<br /><br /><b>13 Killer Sudoku (48 points)</b><br />The recent trend for Killers with a reduced number of cages continues - in this case the cages were all of size 4. This was a nice puzzle, probably my favourite of the set, but definitely undervalued.<br /><br /><b>14 Placement Sudoku (55 points)</b><br />More of a puzzle-y type, albeit not particularly difficult. GM Puzzles refers to these as Shape Sudoku. My solve was a bit dopey and probably took twice as long as it needed to. You'll never guess what the shapes to be placed in the grid ended up being...<br /><br /><b>15 Figure Sum Sudoku</b><br />Again a puzzle-y type to fit the tetromino theme. I think this probably crosses the line over what I'd like to see included in the Sudoku GP. I didn't solve this in time as after making a start I couldn't see further logic. After time, I went into a more puzzle solving mode, went with a configuration which seemed likely and had solved the puzzle 3 minutes later.<br /><br />So, I'd left 5 puzzles with 1 mistake - not anywhere near finishing (albeit that 4 of the remaining puzzles, as well as the mistake were low points) which is a bit disappointing, but I don't think I was completely on top solving form. I think the results tend to show that there was probably one too many puzzles here, even if the top solvers were around the 1 hour 5 mark again, which is at least vaguely consistent with most of the other rounds in this series.<br /><br />Top 3:<br /><blockquote class="tr_bq">1. Tiit Vunk (859.7 points)<br />2. Prasanna Seshadri - a.k.a our esteemed and remunerated WPF director (834.3)<br />3. Jan Mrozowski (811.2)</blockquote>As for the Brits - a little disappointing:<br /><blockquote class="tr_bq">56. Tom Collyer (426)<br />69. Mark Goodliffe (397)<br />71. Heather Golding (390)</blockquote>For the overall, Mark sits on 2658 and Heather is on 2588 from their best 6. I have only had 5 scoring rounds, hitting 2289, which means I need at least 300 to catch Heather and 370 to catch Mark (not taking into account any improvements they make on their worst score) for Round 8 - which I'd expect to do based on my scores so far. <br /><br />Adding 600 to my score takes me to 44th place, and with 40th currently 696 points ahead, that top 40 placing is very much looking like an outside bet - this would require finishing the set with at least 10 minutes to spare, which is in all likelihood a top 10-20 performance. Let's see how it goes! Unknownnoreply@blogger.com3tag:blogger.com,1999:blog-2031071943178978556.post-54476970070709757842017-06-29T01:00:00.000+01:002017-06-29T01:02:40.523+01:00UK Championships ReviewThis weekend saw the UK Puzzle Championship, a contest I believe that has in recent years eclipsed both the much celebrated and long running US Puzzle Championship as the best one-off puzzle contest on the web, and indeed also the WPF's Puzzle GP series. In the first instance, I think the UKPC offers greater flexibility and a better balance of puzzles, and in the second instance I believe it offers a far more interesting variety of puzzles over a more testing time period (albeit this year was 2 hours rather than the usual 2 1/2 hours).<br /><br />First of all the results:<br /><blockquote class="tr_bq">1. James McGowan 588 pts<br />2. Adam Bissett 403 pts<br />3. Tom Collyer 402 pts</blockquote>First of all, congratulations to James and Adam, who both now qualify for the world championships. Having also finished 3rd in the UK Open championship I have very narrowly missed out on the A team.<br /><br />They say bad luck comes in threes. I have a particularly good sob story/bout of sour grapes this time round, probably best filed under couldawouldashoulda, and which perhaps my dearest readers would care to hear about. Maybe not. Either way I feel I need to get this off my chest, so here goes. <br /><br />Exhibit A is my wireless printer, which somehow dropped off the network for the first 10 minutes of the 2 hours (despite having printed the instructions an hour beforehand absolutely flawlessly) meaning the start of my solve was restricted to paint. I feel this didn't go my way when I wanted to submit my answer to the Two Step Maze about 30s after the end of the test.<br /><br />Exhibit B is the piece of paper containing puzzle number 5 (Double Block) and number 6 (Touching Pentominoes) which I carelessly misplaced when entering answer keys, thereby not scoring for these puzzles.<br /><br />Exhibit C is a classic Dickhead Error in misreading the answer code to battleships. The puzzle was solved correctly, but I mistook a clue outside the grid for an answer key coordinate and therefore the answer key was not. Whilst I'm very grateful my appeal for partial points was upheld, this still meant not getting the full points amount.<br /><br />Sooooo... I could have got by with any 2 of these 3 exhibits and still finished in 2nd place. But as it happened, events have conspired against my and I'm left feeling in equal parts: (1) an absolutely idiot with only myself to blame; (2) very sore about not qualifying for the WPC; and (3) a little guilty about highlighting this all as I'm entirely confident that the UK team of Neil, David, James and Adam is going to do the UK proud. I'm not posting all this in expectation of any sympathy - rather I didn't think it was particularly healthy keeping it all to myself.<br /><br /><br />Two weekends also saw the UK Sudoku Championship. I am a little more removed from this as I actually ran and organised the contest, as well as authored all of the puzzles.<br /><br />I hope the competition went well. I have been doing it for several years now, and how I have run this contest over the years definitely influenced my stint as Competition Director for the WPF's Sudoku GP series. My aims for the contest have always been to (1) give UK solvers a decent chance of finishing the set within 2 hours, and (2) maintaining a certain amount of consistency and familiarity in order to promote the contest.<br /><br />I'd like to think that I achieved these aims in 2017, and that the UKSC represents a competition held in similar esteem as the UKPC - but that's not really for me to say. What is for me to say is to congratulate the UK solvers who filled out the podium:<br /><blockquote class="tr_bq">1. Mark Goodliffe - 804 pts<br />2. Heather Golding - 734 pts<br />3. Neil Zussman - 630 pts</blockquote>Both Mark and Heather finished the set, and join myself and David in qualifying for the WSC. I am very happy to be on the team with these three, and I hope we can come close to matching the best ever UK team result (6th, in 2010) - something I believe is well within reach as I think we are all individually capable of finishing in the top 40. Having not made the WPC, the WSC will definitely be my priority. Having thrown away an eye-watering amount of points last year and still finished 25th, I also hope I can beat my best ever finish of 23rd. I guess time will tell!Unknownnoreply@blogger.com3tag:blogger.com,1999:blog-2031071943178978556.post-12068331648073099312017-06-25T23:47:00.001+01:002017-06-26T00:48:20.920+01:00Blog UpdateSo a couple of things have happened over the last couple of days. Most importantly on the typography front, I've decided Times New Roman makes for lovely display, and that there are some acceptable other typefaces languishing in the google font foundry. <br /><br />I'm rearranging other content from the blog as best I can, and there might even by the odd new tit-bit here or there. For example my PhD thesis! I'm also experimenting with the "jump break" feature. At first glance this looks as if it might be immensely irritating to my dearest readers, but I also appreciate that I sometimes waffle on insufferably and this might give people a chance to navigate these choppy waters.<br /><br /><a name='more'></a>Puzzles this year haven't really happened. I think Friday puzzles might be dead as a concept, but I'll try my best to post puzzles as and when I can. I'm not really a fan of releasing puzzles in the awful PNG format that I do currently, so perhaps I'll work a little bit on working on some better formatted PDF content. This will probably incentivise me to sort out some web scripts which everyone can use. No concrete promises, but I feel this is an area where I can really make a difference to the puzzle community. Without wanting to piss anyone off in particular, I see a lot of god-awfully formatted puzzles and it wouldn't take too much work on my part to make everything better for all concerned.<br /><br />I suspect that puzzles won't be the only thing appearing on my blog. I have given up on Facebook for the time being, and I might start making blog functionality from about 10 years ago a thing here - i.e. as an outlet for my own thoughts, be that current affairs, be that the banking industry I work in, or anything else worth a mention. The caveat I give to myself is to at least think things before I post, making sure that I'd raise any content I post as part of a spoken conversation elsewhere. Apologies in advance to anyone who previously followed my blog for the puzzles only.Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-2031071943178978556.post-2947085731169092682017-06-15T22:47:00.000+01:002017-06-25T00:51:48.490+01:002017 Sudoku GP: Round 6 SerbiaA couple of weekends ago, a few nutjobs got a bit stabby in the London Bridge area of London - an area that is about half a mile from where I live. I don't want to give them any coverage in particular, but what with everything going on I completely forgot to take part in round 6 of the Sudoku GP, "hosted" (I'm not sure that's exactly the right word) by Serbia.<br /><br />I've gone away and solved the puzzles, not quite under time pressure as I got interrupted towards the end. Nevertheless, I've done a review:<br /><br /><b>Enjoyment: </b>N/A (doesn't seem appropriate without the full competition experience)<br /><b>Classics: </b>6/10<br /><b>Favourite Puzzle: </b>Dead or Alive Arrows Sudoku<br /><br />Unfortunately missing this round means I've hit a 0 for writing the UK round, and a 0 for this round, so everything else is going to count. I really need a good couple of last rounds - I suspect the final UK reckoning is going to be very tight between Heather, Mark and myself.<br /><br /><div><a name='more'></a><b>1-5 Classic Sudoku (28, 30, 41, 37, 29 points)</b></div><div>These were fine, and a good solid level of difficulty, but a bit disappointing to not have clue symmetry. The solving was also a bit same-y - if I'd have to guess (I don't know, I certainly might be wrong!) then I'd say they'd come from a generator.</div><div><br /></div><div><b>6 Cloned Shape Sudoku (37 points)</b></div><div>I found the shaded groups on top of the grid to be a little annoying, but it didn't hinder the solve. I'm pretty sure the rules of Clone Sudoku cover this so I'm not sure the new name was entirely warranted. I made a small mistake on the first pass, but the puzzle itself solved nicely.</div><div><br /></div><div><b>7 Ratio Sudoku (55 points)</b></div><div>Seemed to solve smoothly enough. It was a little fiddly in places but the points here seem generous to me.</div><div><br /></div><div><b>8 X-Sums Sudoku (47 points)</b></div><div>The opening to the puzzle reminded me of a puzzle I have recently written. This did not stop me making a stupid error (writing 53 next to the 8 clue in the top right) on the first pass, but again this solved nicely enough</div><div><br /></div><div><b>9 Sum Nine Sudoku (28 points)</b></div><div>This is equivalent to (No) Tens Sudoku, with the 9 in this puzzle playing the role of 5 in Tens (indeed it could also play the role of 1 in "Elevens"). I used this variation in the 2014 WSC, primarily because I had a bunch of puzzles which didn't have a given 9 in them but which never quite made it into a more coherent theme. I think I called it No Nines Sudoku. The points here seemed to be slightly stingy.</div><div><br /></div><div><b>10 Antikinght Sudoku (46 points)</b></div><div>I think I may have mentioned "Anti-Knight" previously. Oh well. I've also mentioned it's a type I need a bit of improvement on (Diagonal is the other), and I had to start this, move on, and come back to it. Fairly standard fare though, nice enough.</div><div><br /></div><div><b>11 Diagonal Skyscrapers Sudoku (69 points)</b></div><div>Skyscrapers Sudoku usually leave me a little cold, particular when you have a bunch of givens. I just think that the logic in skyscrapers works perfectly well as a Latin square, and the 3rd box constraint that sudoku imposes just gets in the way. Anyway, solved nicely enough, a bit fiddly perhaps.</div><div><br /></div><div><b>12 Average Arrows Sudoku (87 points)</b></div><div>This is probably verging more into "Puzzle" territory - I certainly had a lot of annotation outside the paper trying to work out the combinations along various arrows. Not really to my taste I'm afraid, but probably worth the points as it was challenging.</div><div><br /></div><div><b>13 Dead or Alive Arrows Sudoku (66 points)</b></div><div>I don't like the name here. I particularly disliked the presentation - the borders on the arrows were much too thick (looks like 1px, instead of a recommended 0.5), too dark (looks like black rather than a recommend light grey) and basically made writing in the grid very frustrating as it was very hard to tell what you had written. I am not at all surprised there were lots of mistakes on this puzzle. That all said, it is a very nice extension of the eliminate variant and I think it works well. The arrows also made a lovely GP motif in the grid, and I think despite the sub-optimal graphics and title this is still my favourite puzzle from the round.</div><div><br /></div><div>Top 3:</div><blockquote class="tr_bq">1. Bastien Vial-Jaime (869.3 points)<br />2. Seungjae Kwak (856.8)<br />3. Hideaki Jo Japan (845.2)</blockquote><div>Spyridon Sofos of Greece finishing in 11th place is a new name to me.<br /><div><br /></div><div>Brits:</div><blockquote class="tr_bq">1. Mark Goodliffe (465)<br />2. Heather Golding (442)<br />3. Michael Collins (366)</blockquote></div><div>Mark on 2586 points is slightly ahead of Heather on 2564 points - both having done all 6 rounds. At this stage, they are both looking to improve on their two weakest rounds to push their scores up.</div><div><br /></div><div>I have done 4 rounds and have 1863 points. I have two rounds left to go, and my target is to get as close to 3000 as possible, and ideally beat that. Optimistically I might finish 30th, but I suspect this will be closer to 40th, plus or minus a couple of places.</div><div><br /></div><div>Whatever happens, i think all 3 of us will beat the previous best series result for the UK, which was Mark's 55th in 2016.</div>Unknownnoreply@blogger.com1tag:blogger.com,1999:blog-2031071943178978556.post-59547462319843449772017-05-26T17:55:00.002+01:002017-05-26T19:39:45.092+01:00Friday Puzzles #301Skyscrapers Sudoku this week. (I haven't got around to my backlog yet). Numbers represent heights of buildings, where bigger numbers block smaller numbers. Clues outside the grid indicate how many different buildings are visible.<br /><br />Enjoy.<br /><br />Edit: previous version had an error. Hopefully that's fixed now.<br /><blockquote class="tr_bq"><b> #342 Skyscrapers Sudoku</b> – rated <b>medium</b><a href="https://1.bp.blogspot.com/-mAjFgznc1NI/WSh2YZSPndI/AAAAAAAAB_4/ANM8-vbfxfIgcLVmm44aJKGGDJsGL1GAwCLcB/s1600/342sky-su%2Bfixed.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="531" data-original-width="531" height="320" src="https://1.bp.blogspot.com/-mAjFgznc1NI/WSh2YZSPndI/AAAAAAAAB_4/ANM8-vbfxfIgcLVmm44aJKGGDJsGL1GAwCLcB/s320/342sky-su%2Bfixed.png" width="320" /></a></blockquote>All puzzles © Tom Collyer 2009-17.Unknownnoreply@blogger.com1tag:blogger.com,1999:blog-2031071943178978556.post-74861628689563156842017-05-12T23:34:00.005+01:002017-05-12T23:34:54.794+01:00Friday Puzzles #300How appropriate to celebrate a nice round number by being nearly-but-not-quite late!<br /><br /><br />Clues outside the grid indicate the "property" of the first two numbers placed in the corresponding direction. Odd=1,3,5,7; Even=2,4,6,8; Big=5,6,7,8; Small=1,2,3,4.<br /><br />Enjoy!<br /><blockquote class="tr_bq"><b> #341 Odd-Even-Big-Small Sudoku</b> – rated <b>medium</b><a href="https://4.bp.blogspot.com/-v3ck5Q7QzyY/WRY4QcD5klI/AAAAAAAAB_U/du7lQXKzdy4B2fugBQg6ha4DexA37kqrwCLcB/s1600/341oebs-su.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://4.bp.blogspot.com/-v3ck5Q7QzyY/WRY4QcD5klI/AAAAAAAAB_U/du7lQXKzdy4B2fugBQg6ha4DexA37kqrwCLcB/s320/341oebs-su.png" width="320" /></a></blockquote>All puzzles © Tom Collyer 2009-17.Unknownnoreply@blogger.com1tag:blogger.com,1999:blog-2031071943178978556.post-88362275593497534942017-05-09T00:08:00.002+01:002017-05-09T00:09:11.894+01:002017 Sudoku GP: Round 5 EstoniaSo hopefully there will be no further barrage of comments this time round, nothing too controversial going on here! The authors this time round were the world champion, Tiit Vunk, and Rauno Parnits. I can't personally recall any more than the occasional puzzle from either author, but this time round there was a pretty heavy chess theme to the round. And although a theme is nice to have, more important in my eyes is a good solid set of fun puzzles to solve, and that's what we got with this set. The vital stats according to me were:<br /><br /><b> Enjoyment: </b>7/10<br /><b>Classics: </b>7/10<br /><b>Favourite Puzzle: </b>Chess Kings Sudoku<br /><br />Anyhow, on to the review.<br /><br /><b>1-6 Classic Sudoku (18, 20, 16, 43, 20, 40 points)</b><br />I tend to like the classics being arranged in the order of difficulty, but I suppose the gimmick here were the patterns of givens, which were respectively a King, Queen, Rook, and a Bishop. This was followed by "b1c3" which I don't quite get (a Knight's opening?), and then "1/2" which I suppose is a draw. Nothing particularly difficult, nothing overly easy (despite some fairly low points totals) - I think the last one had some colouring going but generally a solid set of classics<br /><br /><b>7 Diagonal Sudoku (43 Points)</b><br />Another bishop shaped set of givens, I suppose this makes a lot of sense for a Diagonal puzzle.<br /><br /><b>8 Fortress Sudoku (39 points)</b><br />One of my favourite Fortress puzzles of recent memory. I don't much like the type, but this was remarkable firstly for (1) the clever use of a checkerboard pattern as the fortress with row numbering to the side, and (2) solving cleanly without me making a stupid mistake.<br /><br />Scratch that, it's another fortress puzzle I've cocked up. This is utterly bizarre. I need to go away and practice these for a week until I stop cocking them up.<br /><br /><b>9 Queen Sudoku (69 points)</b><br />I definitely prefer the plural "Queens". This was nice enough for the points, but I do think this type suffers a little bit because as soon as you try and make one with any kind of difficulty it's very tempting just to guess the placement of the queens. The non-attacking constraint is pretty strong, which pretty much guarantees a quick contradiction if you happen to make a bad guess, and easy enough to double check if you make a good guess sans contradiction. Which I did.<br /><br /><b>10 Battenburg Sudoku (73 points)</b><br />Nice to see this type make an appearance. This is generally quite a puzzle-y type as the key to solving these is by first determining whether a particular cell contains an odd or even placement, with the converse rule also needing to be used heavily to make any headway.<br /><br />I am not a fan of the phrasing "all such patterns are marked". I think it is far more friendlier to newer solvers to explicitly say "where there is no marking, there can be no pattern". It feels like I'm banging the same old drum here, but really we do ourselves no favours as a community when we make things harder than they need to be.<br /><br /><b>11 Antiknight Sudoku (85 points)</b><br />I made the strategic error of leaving this puzzle until last, and my placing suffered massively for it. It didn't feel particularly remarkable to me, just a tough version of a type I personally don't enjoy all that much.<br /><br /><b>12 Sum 10 Twin Sudoku (37 points)</b><br />Well done me for solving this without submitting an answer. An otherwise pleasant clone style variant.<br /><br /><b>13 Chess Kings Sudoku (44 points)</b><br />My favourite of the round, and a surprisingly elegant extension of the "No Touch" variant. The example for this novelty had the gimmick that you could isolate the pair of kings by considering the centres of the 3x3 boxes. This logic left me with 1,3,4,7,8 as the possible kings, and although this still leaves a possible 10 different pairs, actually these were eliminated almost instantly leaving the rest of the puzzle to solve nicely.<br /><br /><b>14 Unicorn Sudoku (53 points)</b><br />The constraint feels very very strong for this novelty, and I only used it around three of the placed 9's to solve the puzzle. I think it's probably stretching the chess theme a little thinly, and I don't think we'll see too many more of this type, but it solved pleasantly enough.<br /><br />I had to take this test last on Monday in a bit of a rush, and my solving performance was down. It definitely wasn't helped by not submitting an answer to one of the puzzles. The preliminary results have now been released and it does looks like there have been a fair few mistakes. I ended up with 12/14 puzzles correctly solved, 11 submitted, 1 stupid error, and perhaps a couple of minutes extra required to finish the anti-knight.<br /><br />Despite a disappointing result, and a mix of variants which aren't necessarily to my advantage, I did enjoy this round a lot, and hope that the remaining rounds can match this standard.<br /><br />Top 3 (preliminary results):<br /><blockquote class="tr_bq">1. Jakub Ondrousek (882.8 points)<br />2. Jan Mrozowski (872.3)<br />3. Sinchai Rungsangrattanakul (847.7)</blockquote><div>I had to scroll down much further than I cared for to find my result, and I was surprised to see that I was just two places behind Dr. Snyder, who had 2 errors costing over 25% of the points plus bonus. I suppose I shouldn't complain too much. Commiserations also to Tantan Dai, who informed me of further computer problems which meant her initial submission of under one hour (a score in excess of 900) was not received by the server. Even then, re-submitting the answers via tapping them out on a mobile phone in an extra 10 minutes was still good for an incredible 6th place, and the current overall lead of the GP (see the link below).</div><div><br /></div><div>As for the Brits:</div><blockquote class="tr_bq">35. Mark Goodliffe (561)<br />51. Heather Golding (483)<br />68. Tom Collyer (439)</blockquote><div>Submitting my extra puzzle would have pushed me to 476 points, and 54th place, highlighting the magnitude of the blunder of leaving the anti-knight until last. Mark's performance is the best British score in any of the rounds this year, and represents a really strong solve - congratulations!</div><div><br /></div><div>What is definitely interesting is <a href="http://gp.worldpuzzle.org/content/wpf-gp-sudoku-results-2017" target="_blank">this page</a> - which highlights that Mark and Heather are separated by a single point over 5 rounds. Granted the dropping of the two worst scoring rounds will start coming into play here, but it's fascinating to see who will come out on top here.</div><div><br /></div><div>I'm pretty confident I'm going to need to score bonus time on at least 2 of the remaining 3 rounds if I'm going to end up where I'd set my eyes upon at the start of the season. I'm not sure this is looking very likely at the moment!</div><div><br /><br /></div>Unknownnoreply@blogger.com6tag:blogger.com,1999:blog-2031071943178978556.post-12446981595595655782017-05-05T13:53:00.000+01:002017-05-05T13:53:26.330+01:00Friday Puzzles #299I've got a backlog of puzzles that will hopefully be unleashed either later today or else next week.<br /><br />This one is x-sums. The clues outside the grid indicate the sum of the first X placed numbers in the corresponding direction.<br /><br />So for example a clue of 6 could have X=2, in which case the second placed number would have to be 4. Or, it could have X=3, in which case the second and third placed numbers would have be to 1 and 2 in some order.<br /><br />Enjoy!<br /><blockquote class="tr_bq"><b> #340 X-Sums Sudoku</b> – rated <b>easy</b><a href="https://4.bp.blogspot.com/-U1meUDe_WEQ/WQx1hI4FYzI/AAAAAAAAB_E/Zdxx31G_eloJDPsNOG_0KU0OQN0Dluj1QCLcB/s1600/340xsums-su.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://4.bp.blogspot.com/-U1meUDe_WEQ/WQx1hI4FYzI/AAAAAAAAB_E/Zdxx31G_eloJDPsNOG_0KU0OQN0Dluj1QCLcB/s320/340xsums-su.png" width="320" /></a></blockquote>All puzzles © Tom Collyer 2009-17.Unknownnoreply@blogger.com1tag:blogger.com,1999:blog-2031071943178978556.post-57819805053343397302017-04-11T23:26:00.000+01:002017-04-11T23:26:30.867+01:002017 Sudoku GP: Round 4 United KingdomFirst off - the last couple of weeks of Friday Puzzles have been delayed for one reason or another. Hopefully I can catch back up this week and post 3 puzzles this coming Friday.<br /><br />Secondly, although I have been quite free with my opinions about this year's Sudoku GP thus far, if you think I have the temerity to rate my own puzzles - then you have another thing coming, dearest reader. Nevertheless, I thought it'd be worth offering an author's (rather than ex-director's) view on this round's puzzles, which I co-authored with my good friend/bitter solving rival, David McNeill.<br /><br /><b>1-6 Classic Sudoku (25, 17, 20, 25, 47, 30 points)</b><br /><br />So I hope this represented a decent selection of classics. Certainly no puzzle was what I'd call a guessing puzzle. David's were puzzle 2 and 6, the rest were mine. Puzzle 1 is probably a lot easier if you start by placing all the 1s, then the 2s and so on. This is a standard nikoli gimmick for easy puzzles that I like to throw out every now and again. It works better if you aren't necessarily expecting it; over using it wears thin very quickly. 5 was the hardest, perhaps notable because it needed a few naked singles to get going.<br /><br /><b>7 Diagonal Sudoku (31 points)</b><br /><br />David's puzzle - not sure there's too much to say other than a pleasant enough Diagonal puzzle<br /><br /><b>8 Antidiagonal Sudoku (33 points)</b><br /><br />Mine (and I prefer Anti-Diagonal) - This was nearly a very good puzzle of 16 givens, but I couldn't quite get it to solve uniquely. I'd have persisted with this a lot longer had this been say, for a world championships. This would have fitted in well with a couple of other 16 given puzzles in Round 2 of the 2014 WSC, and might be something I end up revisiting. Watch this space.<br /><br /><b>9 Windoku (58 points)</b><br /><div><br /></div>Mine - I really quite like Windoku as a type, with its 4 visible extra regions and additional 5 implied extra regions. At first glance you might think I was going for another 16 digit puzzle and had to add another given in the middle to get to 17, but no, that's not what I was going for this time. Perhaps the more observant of you will have noticed the centre 9 givens form a magic square? Anyhow, a reasonably tough windoku, as far as these things go, but I suppose if you've done a few of my puzzles you'll have got through this steadily enough.<br /><div><br /></div><div><b>10 Antiknight Sudoku (36 points)</b></div><div><br /></div><div>David's (and I prefer Anti-Knight) - I suspect he was going for a 17 given puzzle here and had to add the corner givens to get this out uniquely. Other than that, a pleasant enough Anti-Knight solve.</div><div><br /></div><div><b>11 Disjoint Groups Sudoku (56 points)</b></div><div><br /></div><div>David's - I always think that half the issue with disjoint groups sudoku on paper is visualising each of the 9 disjoint groups. When solving I often have to draw shapes in the cells to help with that. This puzzle has a nice UK theme, and is potentially a tricky solve if you struggle to visualise the groups, but if you are comfortable with the type I think solves quite nicely.</div><div><br /></div><div><b>12 Irregular Sudoku (40 points)</b></div><div><br /></div><div>David's - the temptation with nicely designed irregular puzzles is to push the difficulty to an extreme, or else to go to extremes using the grid's geometry to shape the solve. I think David hit a nice medium here - the first comment I gave when testing this was that I assumed a couple of the givens weren't strictly needed (in the sense that removing them would still give a puzzle that solved uniquely) and that it felt like an easy solve - but checking my time it was clear that this wasn't a trivial puzzle and instead the feeling that it had gone quicker is a reflection on how nicely the puzzle solved.</div><div><br /></div><div><b>13 Renban Killer Sudoku (63 points)</b></div><div><br /></div><div>David's - normally I'm sceptical about combining together too many rules, but the combination of Renban groups and Killer cages combines really nicely and I think David is really on to something with this variant, which he has made his own. Another nice example</div><div><br /></div><div><b>14 Cloned Strands Sudoku (33 points)</b></div><div><br /></div><div>David's - I'm pretty sure David invented this type primarily to draw funny pictures of animals. And a nice illustration that novelties don't have to (a) have overly complicated rules and (b) have overly difficult solving logic.</div><div><br /></div><div><b>15 Total Blackout Sudoku (86 points)</b></div><div><br /></div><div>David's - blackouts tend to have quite fiddly solving paths, so the gimmick with the sums of the cells around the cells helps to give this type a bit more flavour, as well as providing a nice pun for the variant. I think most of the points value here comes from firstly the novelty value of the variant, and second of all the slightly fiddly bit of logic needed to resolve the top right of the grid.</div><div><br /></div><div>Top 3 (preliminary results):</div><blockquote class="tr_bq">1. Kota Morinishi (850.3 points)<br />2. Tantan Dai (845.5)<br />3. Tiit Vunk (790.2)</blockquote><div>It looks as if there is a strange result for 11th (Huxuan Yu) who has a lower points total than 10th, despite the fact he managed to solve the puzzles nearly 3 and half minutes faster, going by submission time. It's my strong suspicion that this is another case of the failure of the claim bonus button, an issue that has been plaguing the GP for years, particularly for Chinese solvers. I hope an appeal is made or someone notices this before the results are made final.</div><div><br /></div><div>As for the Brits:</div><blockquote class="tr_bq">45. Heather Golding (478)<br />68. Mark Goodliffe (380)<br />99. Michael Collins (334)</blockquote><div>Also good to see there was a relative strong UK turnout of 18</div>Unknownnoreply@blogger.com27tag:blogger.com,1999:blog-2031071943178978556.post-61322765751333625472017-03-24T13:27:00.002+00:002017-03-24T13:27:30.448+00:00Friday Puzzles #298I've run out of time to add the final polish, but there should still be enough here to keep you busy. Cages are clued with the sums of numbers to be placed inside them; no repeats within cages.<br /><br />Enjoy!<br /><blockquote class="tr_bq"><b> #339 Killer Sudoku</b> – rated <b>medium</b><a href="https://3.bp.blogspot.com/-6RR3MnOvMvI/WNUeeJSpccI/AAAAAAAAB-U/P5chxZ4U5zMMQV7V3e7m4Bee0emtmDZJgCLcB/s1600/339ks.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://3.bp.blogspot.com/-6RR3MnOvMvI/WNUeeJSpccI/AAAAAAAAB-U/P5chxZ4U5zMMQV7V3e7m4Bee0emtmDZJgCLcB/s320/339ks.png" width="320" /></a></blockquote>All puzzles © Tom Collyer 2009-17.Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-2031071943178978556.post-13678355841215400972017-03-17T13:58:00.002+00:002017-03-17T13:58:53.276+00:00Friday Puzzles #297Non-Consecutive Sudoku this week. Cells that share an edge are not allowed to contain consecutive numbers.<br /><br />Enjoy!<br /><blockquote class="tr_bq"><b> #338 Non-Consecutive Sudoku</b> – rated <b>medium</b><a href="https://4.bp.blogspot.com/-MBx-NicEwa0/WMvrPmYgRHI/AAAAAAAAB-E/3It0YjJ8sZguZK4Tp_Gb7Yx-c37hQKOQgCLcB/s1600/338ncs.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://4.bp.blogspot.com/-MBx-NicEwa0/WMvrPmYgRHI/AAAAAAAAB-E/3It0YjJ8sZguZK4Tp_Gb7Yx-c37hQKOQgCLcB/s320/338ncs.png" width="320" /></a></blockquote>All puzzles © Tom Collyer 2009-17.Unknownnoreply@blogger.com1tag:blogger.com,1999:blog-2031071943178978556.post-2069407543463443122017-03-14T22:58:00.002+00:002017-03-19T19:55:47.541+00:002017 Sudoku GP: Round 3 Czech RepublicSo on to round 3 of the GP. Again I'm writing most of this straight after solving without being able to reference the results. The authors this time were individual world champion in waiting, Jakub Ondrousek, and probably the world's most prolific Sudoku author, Jan Novotny.<br /><br />To start off, I think that the balance was better than the previous round, but it still wasn't quite right and the puzzles didn't quite have the redeeming feature of being as dazzling brilliant as Bastien's puzzles. Don't get me wrong, comparing less favourably than Bastien is nothing close to an insult; these puzzles were good, and occasionally great, but nevertheless the comparison is there and I'm calling it as I see it.<br /><br />I should probably also <a href="http://gp.worldpuzzle.org/content/publishing-instruction-booklet" target="_blank">draw some attention to controversy</a> before the round. I didn't see this, but apparently the instruction booklet was leaked onto an external website before it went live on the GP website.<br /><br /><b>EDIT:</b> <a href="http://gp.worldpuzzle.org/comment/9376#comment-9376" target="_blank">exactly<b> </b>how this happened has now been explained</a> - in the interests of balance I would encourage you to read what Jan has to say. I do have some sympathy for the desire to encourage new solvers.<br /><br />However my opinion is this remains inexcusable - and whilst I doubt many solvers gained much of an advantage from this, it still looks bad and definitely tarnishes the reputation of the WPF and the GP in my eyes. I can only imagine how frustrating this will be to the competition director.<br /><br />That unfortunate episode aside, here are how I rate the vital stats for the round:<br /><br /><b>Enjoyment: </b>5/10<br /><b>Classics:</b> 3/10<br /><b>Favourite Puzzle:</b> Pointing Differents Sudoku<br /><br />Let me add again that enjoyment for me is a personal thing, and is affected by how well I thought i was solving as well as the overall quality of the round - which by and large was of a good standard. Without further ado, here's the review: <br /><br /><b>1-5 Classic Sudoku (15, 12, 12, 10, 54 points)</b><br /><br />Just looking at that points distribution tells you the whole story. The first four were easy to the point of being trivial. The last - I've confirmed with scanraid - was a guessing puzzle. These always leave a bad taste in my mouth and I whole-heartedly wish they would stop featuring in competitions. Please authors and competition directors, enough of these puzzles! <br /><br />As for the first four puzzles, although you can see there was a visual gimmick with first the Czech flag, and then a C, then Z, then E theme, I think this is a prime example of where the theme of the puzzle proves to be a negative rather than positive. Nice enough puzzles I suppose, but these were simply too easy. The fact that the classic contingent made up less than 100 of the 600 points on offer also points to a bad balancing of the competition, in my opinion. <br /><br /><b>6 Overlapping Sudoku (44 points)</b><br /><br />I suppose you might generously say that overlapping might count towards the classic contingent of puzzles, which puts the balance up to a less unflattering 25% of the points for classics. The puzzle solved nicely, although I do wonder about the presentation here. I'd be interested to try this with one of the overlapping grids shaded grey - I generally find the dotted lines for the 2nd grid to be a little distracting - but it's hard to say whether this can definitely be improved without a bit of experimentation. Aside from this, it started a run of "CZ" themed variants.<br /><br /><b>7 Diagonal Sudoku (47 points)</b><br /><br />A nice enough diagonal puzzle, with a CZ theme.<br /><br /><b>8 Odd Sudoku (21 points)</b><br /><br />There were probably more givens here then strictly necessary, but given the remaining variants in the round were all quite difficult, a nice easier variant was definitely welcome. Again with a CZ theme.<br /><br /><b>9 Nonconsecutive Sudoku (68 points)</b><br /><br />Personally, I prefer "Non-Consecutive" but there we go. Not a particularly polished solving experience, it nevertheless had a fairly narrow solving path which might have left some solvers stumped for a while. Another CZ here!<br /><br /><b>10 Fortress Sudoku (58 points)</b><br /><br />I didn't have time for this in competition, which is probably wise given recent experiences with fortress puzzles. After time, it solved nicely enough. Yes, another CZ theme here!<br /><br /><b>11 Mathdoku (77 points)</b><br /><br />I wasted a lot of time on this during the competition, having felt my way into what felt like an opening. I had then convinced myself that I'd made a mistake. Solving it after time it turned out that I hadn't, I just hadn't considered one remaining option - the correct one! This being the biggest pointer in the competition, this was definitely annoying! Also a temporary reprieve from all those C's and Z's.<br /><br /><b>12 Pointing Differents Sudoku (60 points)</b><br /><br />The clear star of this round, combining elements of diagonal and anti-diagonal all into one puzzle. It was a little fiddly to finish at the end, but really I'm splitting hairs with what was really an excellent puzzle. And the last of the CZ's to boot!<br /><br /><b>13 Fuzzy Arrows Sudoku (58 points)</b><br /><br />I didn't get the logic with this one - after wasting a lot of time on an abortive effort with this one, I managed to guess my way through. Maybe I've missed something clever here, but that in itself is enough to take some of the enjoyment away from solving.<br /><br /><b>14 Lonely Number Sudoku (64 points)</b><br /><br />The massively contrived instructions could only ever point towards a one-off gimmick - I can't see any other authors making much more variant with this type. Once you realised that the lonely number had to be in R5C5, this basically reduced to quite a tricky (but otherwise unspectacular) Touch Sudoku variant. I was quite pleased to get this out in the last 7 or so minutes, whilst fixing what would have been an irritating error with about 10 seconds to spare.<br /><br /><br />So, 12/14 solved in time. There were definitely a couple of tricky puzzles here, but I don't think this will prove as difficult as round 2 and so with the points that I left on the table I'm not going to end up with a particularly good ranking. From a personal perspective, I wasted far too much time trying to do the 5th classic without guessing, and then got bogged down with Mathdoku and Fuzzy Arrows. This happens every now and again, particularly when I'm not quite fully on my game. I would say there's always next round, but I am co-authoring the next round with David McNeill and so won't be taking part.<br /><div style="border: 0px; font-family: 'Lucida Sans', 'Lucida Grande', Lucida, sans-serif; font-size: 13.800000190734863px; line-height: inherit; margin: 0px; padding: 0px; vertical-align: baseline;"><br /></div>Top 3 (preliminary results)<br /><blockquote class="tr_bq">1. Tiit Vunk (855.7 points)<br />2. Seungjae Kwak (809.8)<br />3. Prasanna Seshadri (746.7)</blockquote>As a general comment, it seems like there is a consistent pattern to be observed. Last year the top finisher was typically done in 60 minutes (900 points). This year the top finisher is closer to 65 minutes (850 points) - an early indication that points towards the 2017 series being slightly harder. Alternatively, maybe we collectively haven't quite warmed up yet. Time will tell!<br /><br />As for the Brits:<br /><blockquote class="tr_bq">37. Tom Collyer (465)<br />45. Mark Goodliffe (431)<br />65. Heather Golding (366)</blockquote>Bad luck to Mark, who had submitted 13 answers with 2 errors - without these it looks like he was pushing top 20 for the round, which would have been the best showing so far. Also good to see other UK solvers within an easy puzzle of the top 3: Neil (8 points) and Ned (23 points).Unknownnoreply@blogger.com15tag:blogger.com,1999:blog-2031071943178978556.post-26378449121355817842017-03-10T14:26:00.002+00:002017-03-10T14:28:03.249+00:00Friday Puzzles #296Odd sudoku this week. Only odd numbers are allowed in the shaded cells.<br /><br />Enjoy!<br /><blockquote class="tr_bq"><b> #337 Odd Sudoku</b> – rated <b>medium</b><br /><a href="https://2.bp.blogspot.com/-pSycyGF99-c/WMK3jWzIuzI/AAAAAAAAB9s/1MZf9IhVFcYr0wJkiCM7o0I4w0bd1KdEACLcB/s1600/337.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://2.bp.blogspot.com/-pSycyGF99-c/WMK3jWzIuzI/AAAAAAAAB9s/1MZf9IhVFcYr0wJkiCM7o0I4w0bd1KdEACLcB/s320/337.png" width="320" /></a></blockquote>All puzzles © Tom Collyer 2009-17.Unknownnoreply@blogger.com1tag:blogger.com,1999:blog-2031071943178978556.post-14748971178012358782017-03-03T09:28:00.001+00:002017-03-03T09:28:37.766+00:00Friday Puzzles #295The difficulty this week is turned down a little. Enjoy!<br /><blockquote class="tr_bq"><b> #336 Windoku</b> – rated <b>medium</b><a href="https://1.bp.blogspot.com/-C7T0mi0fZLw/WLk3CPXbCCI/AAAAAAAAB9Y/rUyRnt2aNjwFPtY2wTR1pSfcdMdD1OEHQCLcB/s1600/336win.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://1.bp.blogspot.com/-C7T0mi0fZLw/WLk3CPXbCCI/AAAAAAAAB9Y/rUyRnt2aNjwFPtY2wTR1pSfcdMdD1OEHQCLcB/s320/336win.png" width="320" /></a></blockquote>All puzzles © Tom Collyer 2009-17.Unknownnoreply@blogger.com3tag:blogger.com,1999:blog-2031071943178978556.post-19395512593020758712017-02-24T00:00:00.000+00:002017-02-24T00:00:22.524+00:00Friday Puzzles #294This one is fairly tricky too. Enjoy!<br /><blockquote class="tr_bq"><b> #335 Diagonal Sudoku</b> – rated <b>hard</b><a href="https://4.bp.blogspot.com/--l8r4RBb8u0/WK9k1QzvxEI/AAAAAAAAB9E/dauMmKK7WzoCNjwe4shJIbGWn7fXeOOAQCLcB/s1600/335dsu.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://4.bp.blogspot.com/--l8r4RBb8u0/WK9k1QzvxEI/AAAAAAAAB9E/dauMmKK7WzoCNjwe4shJIbGWn7fXeOOAQCLcB/s320/335dsu.png" width="320" /></a></blockquote>All puzzles © Tom Collyer 2009-17.Unknownnoreply@blogger.com2tag:blogger.com,1999:blog-2031071943178978556.post-60111503215523297732017-02-18T12:30:00.001+00:002017-02-18T12:30:16.821+00:00Friday Puzzles #293Yes it's not Friday any more. This should keep you busy for a while!<br /><blockquote class="tr_bq"><b> #334 Irregular Sudoku</b> – rated <b>hard</b><a href="https://1.bp.blogspot.com/-t_GaZmv9mj8/WKg-Iupaq_I/AAAAAAAAB8U/CpVcNIiLasw2RsITKURbyCj0uVVurqebACLcB/s1600/334isu.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://1.bp.blogspot.com/-t_GaZmv9mj8/WKg-Iupaq_I/AAAAAAAAB8U/CpVcNIiLasw2RsITKURbyCj0uVVurqebACLcB/s320/334isu.png" width="320" /></a></blockquote>All puzzles © Tom Collyer 2009-17.Unknownnoreply@blogger.com2tag:blogger.com,1999:blog-2031071943178978556.post-25037952865577832512017-02-13T23:59:00.003+00:002017-02-14T00:12:13.992+00:002017 Sudoku GP: Round 2 FranceOk, so this was the Bastien Vial-Jaime show. Having known this I was very confident this would end up have the highest quality puzzles of the entire series - and having now solved them I think this is very like to end up beingtrue. If there's a better author around than Bastien then I certainly don't know them - his variants are always fresh and innovative, and the classics he writes always solve beautifully.<br /><br />Nevertheless this round wasn't as fun as round 1 for me, for reasons that have more to do with myself rather than the puzzles themselves. Very often the clever tricks to the puzzles were lost on me and given the time pressure I had to do a bit of bifurcation (to resurrect my favourite euphemism) to get the puzzles out. Also there was a Fortress Sudoku which inevitably I cocked up. It seems to be the rarest of Fortress Sudoku in competitions that I do not break. For what it's all worth, here are the vital stats for the round:<br /><br /><b>Enjoyment: </b>6/10<br /><div><b>Classics:</b> 9/10<br /><b>Favourite Puzzle:</b> Killer Sudoku</div><div><br /></div><div>So onto the review. First thing I'll note is something that I didn't notice last time, but which I did this time. Round 1 the shade of grey was definitely too dark. For this round we are back on track with an acceptably light grey. The difference this makes to solving should not be underestimated!</div><div><br /></div><div><b>1-5 Classic Sudoku (21, 17, 28, 20, 41 Points)</b></div><div><br /></div><div>This being the first page out of the printer, I went straight to the classics. All in all, they were very high standard, with strong distinctive visual patterns of givens that weren't constrained to the traditional 180 degree clue symmetry and in each case guided by clear and smooth solving paths that weren't trivial even for the easiest puzzles. I only knocked off a mark here because I'd have liked to have seen another ~40 point puzzle included -- ideally in place of the Almost Palindrome?</div><div><br /></div><div><b>6 Diagonal Sudoku (72 points)</b></div><div><b><br /></b></div><div>A beautiful puzzle that would have been my favourite puzzle on any other round. Nearly minimal in terms of givens, with a mere 17, they were all populated in the top half of the grid. This meant that the solve elegantly cascaded down through the grid.<br /><br />From a presentational point of view, I'm pretty much converted to having solid diagonal lines rather than dashes.</div><div><br /></div><div><b>7 Figures Sudoku (66 points)</b></div><div><br /></div><div>I had this and an attempt to retry the Fortress with 7 minutes to go, and failed miserably. I tweaked that the figures might actually be extra regions, and used this as a half hearted attempt to get it out in time, but I wasn't successful. It'd be interesting to actually deduce the logic for this some other time as I can't see how you make any progress without realising this. The other note here is that the cages for this puzzle were formatted differently from the cages for Killer Sudoku, which irritated me a little.</div><div><br /></div><div><b>8 Fortress Sudoku (58 points)</b></div><div><br /></div><div>As with many other competition Fortress Sudoku puzzles, this was going very well until suddenly I hit a big contradiction. My attempts to fix this in the last 7 minutes were sadly fruitless. What was doubly annoying was that I caught myself making a false assumption early on in the solve. What would be triply annoying would be when I do go back to solve this, it may well turn out this falsely made assumption may have nevertheless not contradicted the final solution. Ugh. For what it's worth this felt like it was another excellent puzzle.</div><div><br /></div><div><b>9 Renban Groups Sudoku (64 points)</b></div><div><br /></div><div>Perhaps I'm being a bit precious on this one, but I don't really like to see this abbreviated simply as "Renban Sudoku". I corrected this without comment for Round 1, but there, I've made this very minor point here!</div><div><br /></div><div>Semantics aside, this was a lovely puzzle and probably a candidate for favourite puzzle on another round. I did have to accelerate progress with this one with a well chosen bifurcation, which admittedly does take something away from the competition experience (for me anyway).</div><div><br /></div><div><b>10 Thermo Sudoku (36 points)</b></div><div><br /></div><div>A striking design that solved cleanly and elegantly, another excellent puzzle.</div><div><br /></div><div><b>11 Killer Sudoku (84 points)</b></div><div><br /></div><div>Every now again I come across a Killer that I start raving about, and this is one of them. I think I just really like it when the interplay between no repeats in cages and the addition really comes off - you can get a similar thing with extra regions/consecutive with Renban Groups but in my opinion there's an extra layer of solving richness with addition. </div><div><br /></div><div>This was perhaps slightly tarnished in competition as I had to bifurcate to get myself started which meant that again I missed something, but the bits I did get were enough to confirm to me this was a thing of real beauty. </div><div><br /></div><div>I think this is probably one of those puzzles that I might have umm-ed and ahh-ed about including before ultimately liking it too much to throw away, nevertheless I would have to accept this isn't necessarily the same kind of Killer that many less experienced solvers are used to.</div><div><br /></div><div><b>12 Odd-Even Pairs Sudoku (56 points)</b></div><div><br /></div><div>This variant has been around with various names and various presentation, and I think in general whilst I like the name here, I'm not so keen on the use of "capsules" as a presentation. I think I'd prefer to see the shaded Renban Groups style here instead, assuming you really wanted to make the cells prominent - or else to stick with the (more) standard "Pairs" style marking of a circle between the two adjacent cells.</div><div><br /></div><div>That all said, the capsules style presentation for this puzzle did make the puzzle's defining gimmick much easier to spot (i.e. that you had to have odd numbers in R3C3 R3C4 R4C3 and R4C4) and the puzzle again solved cleanly and elegantly after that. Another excellent puzzle!</div><div><br /></div><div><b>13 Almost Palindrome Sudoku (37 points)</b></div><div><br /></div><div>I'm not hugely keen on these "liar" or "almost" constraints in general, and although this one solved nicely enough it's definitely one where the constraint was in parallel with the sudoku solving rather than then augmenting it. A good example of where it does work is with Surplus or Deficit Sudoku. That's just my personal preference, but I don't think this one quite reached the exceptional heights of the rest of the round.</div><div><br /></div><div><br /></div><div>So, 11/13 solved (still no mistakes!), but I didn't feel like I was close to finishing this one, which I think also takes away a little of the enjoyment from solving. I suppose the proof will be in the results, but I suspect this will be perhaps quite a bruising experience for less experienced solvers, and one where experienced solvers really need to be on top form to come away happy. </div><div><br /></div><div>It feels a bit strange to say that perhaps there were too many "clever" puzzles for a competition, but with the clock ticking away I did have to rely on bifurcation more than I'd have hoped and I'd be interested to hear whether this was the same for other solvers.<br /><br />Having initially written most of this post on Sunday, and having now seen the results, it looks like my gut feeling was pretty close to the mark.<br /><br />Top 3 (preliminary results)<br /><blockquote class="tr_bq">1. Shiyu Chen (795.7 points)<br />2. Tiit Vunk (761 points)<br />3. Jakub Ondrousek (692.2)</blockquote></div><div>A new name for me is Nicholas Ling of Australia, finishing in 16th place, which would be pretty impressive going for a newcomer.</div><div><br /></div><div>And for the Brits:</div><blockquote class="tr_bq">27. Tom Collyer (476)<br />53. Heather Golding (372)<br />71. Mark Goodliffe (325)</blockquote><div>Well done Neil for having a go!</div>Unknownnoreply@blogger.com7tag:blogger.com,1999:blog-2031071943178978556.post-77171630446563176522017-02-10T00:00:00.000+00:002017-02-21T23:02:15.378+00:00Friday Puzzles #292Can you tell what it is yet? Small packages can still sometimes pack a punch!<br /><br />1 to 7 once in each row and column, and at most once in each 6 cell region. Enjoy!<br /><blockquote class="tr_bq"><b> #333 Deficit Sudoku</b> – rated <b>hard</b><br /><a href="https://1.bp.blogspot.com/-P_fqmEK5OqQ/WKzGqENaeJI/AAAAAAAAB8s/0Qz4xy5Sou8rIIOW-49vBvsUpX68Na_MQCLcB/s1600/333dsu_fixed.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://1.bp.blogspot.com/-P_fqmEK5OqQ/WKzGqENaeJI/AAAAAAAAB8s/0Qz4xy5Sou8rIIOW-49vBvsUpX68Na_MQCLcB/s320/333dsu_fixed.png" width="320" /></a><br /><i>(A fixed version of a previous puzzle)</i></blockquote>All puzzles © Tom Collyer 2009-17.Unknownnoreply@blogger.com2tag:blogger.com,1999:blog-2031071943178978556.post-35386872026194807502017-02-04T00:13:00.000+00:002017-02-09T23:25:44.130+00:00Friday Puzzles #291Well this would have been on time if my laptop hadn't given up the ghost. How irritating. <br /><br />1-7 once in each row and column, and at least once in each 8 cell region. Enjoy!<br /><blockquote class="tr_bq"><b> #332 Surplus Sudoku </b>– rated <b>medium</b><br /><a href="https://1.bp.blogspot.com/-urY3LOsIJc4/WJz6TEq0HgI/AAAAAAAAB74/IbtVlThwXhEycOjfSsV6waelW_DkxfmLgCLcB/s1600/332ssu.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://1.bp.blogspot.com/-urY3LOsIJc4/WJz6TEq0HgI/AAAAAAAAB74/IbtVlThwXhEycOjfSsV6waelW_DkxfmLgCLcB/s320/332ssu.png" width="320" /></a></blockquote>All puzzles © Tom Collyer 2009-17.Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-2031071943178978556.post-41405426975113630262017-01-27T00:00:00.000+00:002017-01-27T09:26:06.137+00:00Friday Puzzles #290So I think for 2017 this blog may well be just sudoku and variants - however I will be posting links to Grandmaster Puzzles as and when my puzzles there get published.<br /><br />Lets see how it goes, dearest reader. As ever, hope you enjoy!<br /><blockquote class="tr_bq"><b> #331 Sudoku</b> – rated <b>easy</b><a href="https://4.bp.blogspot.com/-hPsZ68t8l5Y/WIqFVeSqXFI/AAAAAAAAB7M/AQDjqV4ku-kdxKeNygDBEml-2CWVoXTZACLcB/s1600/331su.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://4.bp.blogspot.com/-hPsZ68t8l5Y/WIqFVeSqXFI/AAAAAAAAB7M/AQDjqV4ku-kdxKeNygDBEml-2CWVoXTZACLcB/s320/331su.png" width="320" /></a></blockquote>All puzzles © Tom Collyer 2009-17.Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-2031071943178978556.post-91437561369627199052017-01-19T22:42:00.002+00:002017-02-14T00:34:03.187+00:002017 Sudoku GP: Round 1, NetherlandsLast year (2016) I was in charge of the WPF's Sudoku GP series, which was a very interesting and exhausting experience. This year, I've taken a step back and am able to enjoy competing in the competition.<br /><br />My first impressions involve a little disappointment in the downgrade of publication quality - the competition is no longer published using vector graphics, and the typeface has been changed from Helvetica to Arial. The changes are minor and the untrained eye is unlikely to notice any difference, but the major gridlines seemed much too thick to me, especially in comparison with the width of the printed givens, which is unfortunate because the givens do not stand out as much as they should. <br /><br />Minor gridlines cannot be any thinner than a pixel if the graphics are not in vector form (although you can kind of approximate by colouring them grey rather than black), which is unfortunate as this is a big limitation on the ratio of major to minor gridlines. This is a very important ratio in the aesthetic of a sudoku grid!<br /><br /><span style="font-size: x-small;"><i style="font-weight: bold;">EDIT: </i>This is not quite true - whilst the entirety of the IB is definitely not vector format, the CB puzzle grids do seem to be vector format (although bizarrely the text in the CB is not...). In any case the thickness of both minor and major gridlines has increased, which is ultimately the point I am trying to make. </span><br /><br />With regards to the differences between Arial and Helvetica: they are minimal, but the former is a piss poor imitation of the latter when it comes to R's, G's and (most relevant to a Sudoku grid) 1's. The Arial 1 is a nasty piece of work. There, I've said it!<br /><br />All that said, I also know how much work goes into producing work of publication standard. The director's first responsibility is there puzzles - it's a nice bonus if the director also has skills in the area of publication, but otherwise this is all work for a separate role which hopefully the WPF can sort out. From this point I suppose I will try and leave any further comment on publishing unless it it directly impacts the solving experience.<br /><br />So, on to the puzzles themselves. Round 1 of the GP is normally organised in a bit of a rush, particularly if there is a new director settling into the job, so it is great to have reliable hands like Richard Stolk and Arvid Baars who can step up and produce a high quality round at reasonably short notice.<br /><br />From a personal solving point of view, I've historically not fared too well with Richard's puzzles in competition, but I've now also solved a lot of his puzzles and I think I'm getting better. I was therefore optimistic about having a good round and generally getting back to solving at a high standard.<br /><br /><b>1-6 Classic Sudoku (12, 29, 27, 36, 49, 22 points)</b><br /><br />I solved the first four to ease myself into the competition, and they all seemed nice enough. The 5th I came back to a bit later, which was definitely the hardest of the set but pleasingly not at a guessing level. The 6th I had 3 minutes to solve at the end of the round, and rather frustratingly didn't get out in time. Not sure there's too much more to be said about the classics other than they were at the reliably good standard I've come to expect from those two.<br /><br /><b>7 Clone Sudoku (21 points)</b><br /><br />This was easy as the points total suggested, however I cocked this up during the 90 minutes and didn't have time to come back to the fresh copy I printed off. As the mistake came quite early in the 90 minutes this may have thrown me off a bit.<br /><br /><b>8 Renban Groups Sudoku (47 points)</b><br /><br />A reasonably tricky puzzle which I got half way through before setting aside and only came back to much later in the 90 minutes. There was some nice logic determining what a few of the Renban groups were by noting the possible min and max values for the groups<br /><br /><b>9 Sudoku XV (23 points)</b><br /><b><br /></b>It's a bit annoying that XV Sudoku has suddenly become Sudoku XV, but it was definitely annoying that I managed to cock up another easy puzzle without having time to come back to it in the 90.<br /><br /><b>10 Consecutive Sudoku (64 points)</b><br /><br />Very striking given consecutive bars - usually when you have something like this the non consecutive constraint becomes even more important, which makes for a bit of a fiddly solve. This puzzle was a bit like that - a little hard to get in to, which reflects the high points value but once you were the overpowering non-consecutive constraint took over. I suppose puzzles like these are why given the choice I prefer Consecutive Pairs, where the converse rule is not in place.<br /><br />A quick note here on the instructions for this puzzle:<br /><blockquote class="tr_bq"><i>Apply classic sudoku rules. In all cases where two neighbouring cells contain consecutive digits, a grey bar is placed between those cells.</i></blockquote>This is more concise and compact than rules I've written, and the reason for this is because it is not immediately clear to a beginner what the "all" is implying (i.e. that a non-consecutive converse is also in effect). This is dangerous for a puzzle like this that is ultimately dominated by the non-consecutive constraint - it is easy enough to satisfy the grey bars and then arbitrarily fill out the rest of the grid without quite being sure why such an answer is incorrect.<br /><br />As another matter of taste, I much prefer to refer to placing numbers rather than digits. This way you can reserve the term digits for variations which make use of strings of placed numbers. Placing numbers is also a nod towards an early name for Sudoku, which was of course "Number Place".<br /><br /><b>11 No Touch Sudoku (41 points)</b><br /><b><br /></b>Easy enough, but common to this variation its often easy to miss the one thing you need to make progress in the puzzle. This probably took me too long to solve.<br /><br /><b>12 MaxAscending Sudoku (69 points)</b><br /><b><br /></b>A novelty to me, a cute idea but perhaps not a variant with much staying power once a few gimmicks have been explored. This seemed to solve relatively nicely given the high points tally. I'm not quite sure why this isn't "Max Ascending" with a space.<br /><br /><b>13 Mathrax Sudoku (56 points)</b><br /><br />A Richard/Arvid specialty. Both are capable of making this variant really quite tricky, but this one was a little friendlier and didn't cause me too much of a problem.<br /><br /><b>14 Scattered X-Sums Sudoku (53 points)</b><br /><br />X-Sums in an irregular grid is nothing new, and the scattered grid is only a mild relaxation of irregular regions so I don't really count this as a novelty. The overly thick major gridlines provided sufficient contrast with the (overly thick) minor gridlines - I suspect I'd have been quite annoyed if there were givens in the grid being visually overpowered - but there weren't and it solved quite nicely. Probably took longer than it should have, and there was a brief moment at the end where I thought I had another cock up. Luckily for me I was able to fix it.<br /><br /><b>15 Unique Order Sums Sudoku (51 points)</b><br /><b><br /></b>I think I've possibly seen this (or something similar) as a Daily League puzzle in previous years, but this is likely to be novel to most. I didn't think I'd be a big fan of this based on the pig of an example in the IB. Perhaps it's a little too puzzle-y for some tastes, but the observation that there are only 15 unique sums of 2 digits means that it's potentially very quick to ascertain the value of the 12 ordered cages and then solve very quickly as an easy Killer Sudoku. This was the only puzzle I didn't look at in the 90 minutes at all, which is a shame as I'm pretty sure I got it out in the 3 minutes I had at the end.<br /><br />Overall a nicely balanced set, one which I think I might have finished on a good day, but on this day I managed 11/15, scoring 483/600 points. No submission errors is definitely a positive for me!<br /><br /><b>Enjoyment:</b> 8/10<br /><b>Classics:</b> 8/10<br /><b>Favourite Puzzle:</b> Renban Groups Sudoku<br /><br />Top 3 Overall are (results are preliminary at the time of writing):<br /><br /><blockquote class="tr_bq"><i>1. Tiit Vunk (855 points)<br />2. Jakub Ondrousek (853.7)<br />3. Seungjae Kwak (817.8)</i></blockquote><br />Also good to see a return to competition from my GM Puzzles colleague, Thomas Snyder in a very creditable 4th. The competition at the top will certainly be fierce this year.<br /><br />Top 3 UK:<br /><br /><blockquote class="tr_bq"><i>47. Tom Collyer (483)<br />66. Mark Goodliffe (424)<br />67. Heather Golding (423)</i></blockquote><br />I suspect the UK top 3 will be a permutation of these three names, bearing in mind David McNeill isn't participating, and Neil Zussman is just plain lazy. I would love to be proved wrong and have a UK newcomer come to shake things up!Unknownnoreply@blogger.com3tag:blogger.com,1999:blog-2031071943178978556.post-87865235030218066122016-08-07T10:45:00.001+01:002016-08-07T10:47:37.082+01:00Tumbleweedit feels like the tumbleweed has been gathering on this blog for a little too long. Having seen a 10x10 anti-symmetry Masyu authored by my good friend Rob V on croco puzzle early this week, I wanted to see whether I'd lost my touch...<br /><br />Enjoy!<br /><blockquote class="tr_bq"><b> #330 Masyu</b> – rated <b>easy</b><a href="https://3.bp.blogspot.com/-dWhw_EPpMaE/V6cAqiqpXjI/AAAAAAAAB3c/E9kypE3FxGMv9u_GD3byaBMN4UQvHi9dACLcB/s1600/330ma.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://3.bp.blogspot.com/-dWhw_EPpMaE/V6cAqiqpXjI/AAAAAAAAB3c/E9kypE3FxGMv9u_GD3byaBMN4UQvHi9dACLcB/s320/330ma.png" width="320" /></a></blockquote>All puzzles © Tom Collyer 2009-16.Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-2031071943178978556.post-34884282429414427802016-02-05T01:15:00.000+00:002016-02-05T01:15:01.529+00:00Friday Puzzles BreakWell I suppose this post is a bit late, but as a word of explanation to any of my dearest readers who still return to this dusty old corner of the internet every now and again I would like to say that I have been somewhat preoccupied with being ill, and then catching up to prepare Round 2 of the WPF's Sudoku GP. (Why not give it a go!)<br /><br />As such puzzle making has ground to a halt. I don't really have anything to offer this week either, but maybe next week will be different! What I do have, for the masochists amongst you, is a "Darts" puzzle.<br /><br />All you need to do is pick 5 candidate numbers from this list which sum to the given total of <b>2016</b>.<br /><br />120<br />232<br />341<br />350<br />363<br />449<br />482<br />495<br />594<br />615<br />1079<br /><br />I have no idea whether this is easy or whether I have turned things up to 11. What I will say is the intended solving logic reduces things nicely, if you happen to find it!Unknownnoreply@blogger.com0