Beijing International Sudoku Tournament 2012

Thanks for the congratulations that have been given to me both in the Events Calendar under the corresponding topic and IRL. However, since I did not have access to a computer there and currently only the top 10 are listed on the event website and there is no information about the rounds and finals, I will make a short summary of the different rounds, what was there, how I did and how others did. I will make different posts under this topic by round, to make it more convenient and easier to follow:

First about the event itself. On May 17th we went to the site and on May 18th there were excursions. Since last year we visited the Great Wall of China, it was decided that this year we would go to see the famous Forbidden City, which is located in the heart of Beijing. However, since many people did not go last year, we were still offered the opportunity to visit the Great Wall of China and so I did. To tell you the truth, I went to the Forbidden City 2 days earlier, because I took the plunge and went there a little earlier to get used to the conditions. On the one hand, this travel was good, it got my mind off everything - on the other hand, it also made me a little tired, and probably affected my performance at the tournament a little.

I had 30 minutes to solve, and I was given 12 classic Sudoku puzzles of medium difficulty. When the time was up, I had already solved the last one - so 1 remained to be solved. 4 opponents managed to solve it to the end, the best of them finished when there was more than 10 minutes left. So after the opening round, I took 5th place. The opponents who finished were Ondrousek from the Czech Republic, Morinishi from Japan, Mrosowski from Poland and Snyder from the USA. Quite an expected performance considering that I was 5th.

The second round was essentially a round of well-known variants, where 8 sudokus had to be solved within 50 minutes: 1: Special Shape 2: 0-9 sudoku: In each box, one box is divided in half, and in each row, column and box there are numbers 0-9. 3: Non-Consecutive: consecutive numbers cannot be next to each other. 4: Atypical: In this sudoku, the boxes are scattered, so there are 12 3x3 boxes in a 16x16 area. 5: Windoku: Sudoku with 4 extra regions, where 1-9 must also be. When viewed from the side, it resembles a window. 6: Extra-Region: A couple of regions are painted with gray squares, where 1-9 must be. 7: Arrow sudoku: Circles are drawn on the board and arrows come out of them. The number in the circle is the sum of the numbers in the box. 8: Nine Dragons: Essentially a different shape, but instead of the different shaped boxes, there are 9 zig-zag lines drawn, where the numbers 1-9 must be. I managed to finish everything except the Arrow sudoku, I was probably a few minutes short. And surprise surprise, the same 4 main competitors all finished this round. So the gap widened even more, but I maintained my 5th place.

You had to solve 6 sudoku puzzles in 50 minutes. 1: Fortress: If a gray box and a white box are next to each other, the gray box always has a larger number. Otherwise, it's normal. 2: Binary sudoku: The numbers were given as hints in the 2-nd system, and some of the given numbers were partial. 3: Minimal Killer Sudoku: Like a regular killer sudoku, but the number at the top of the box shows the smallest possible sum of the numbers in the box. (If the number is 6, then the sum must be at least 6) 4: Inverse sum: The sum of the reciprocals of the numbers in the first three boxes is given as a clue. For example, if there are 1 2 and 3 in the box, then the sum is 1/1 1/2 1/3 = 11/6, and this was given as a hint. 5: Jigsaw sudoku: You had to place the puzzle pieces correctly on the sudoku board, and solve the sudoku. 6: Bridge sudoku: There is only 1 bridge between each 3x3 box, and there is always a bridge when there are consecutive numbers in adjacent boxes. I had figured out the order of how I was going to do it, and I started solving it. Fortress was the first, and there were no problems with it. I started solving Binary the second, but when I placed the last number (number 5) in the box, it was not possible to put this number there according to the given hint. I tried to find the error, but I couldn't do it. Later it turned out that in box 4, the numbers 1 and 5 had to be swapped. Knowing that there was an error, I just left it there and continued in my planned sequence - so the next one was bridge sudoku, which wasn't difficult, but it took some time. When solving jigsaw sudoku, however, I couldn't somehow place the pieces there. After hearing the solution from others, I was pretty close to the solution, but it doesn't cost anything. After some time, I had a suspicion that if I didn't solve it, then finishing the round with 2 sudokus would still be tough. So I quickly did an Inverse sudoku, which turned out to be extremely easy. Until the end of the round, I tried to find a placement for these pieces, and the result of this round was 3/6, which is a complete failure. I was able to do at least 5. To my surprise, after the 3rd round, I still found myself in 5th place. The first 4, however, had already gone quite far.

I had to solve 8 above-average sudokus in 30 minutes. I hoped to either reduce my gap with the previous ones or increase my gap with the next ones. I managed to finish everything 4 minutes before the time ran out. Of course, Ondrousek finished a little earlier, and I also saw that Snyder had already finished. Mrozowski probably finished earlier too, although I didn't see him. Morinishi finished a minute after me. However, the result was a mistake in one sudoku, which meant that once again the first 4 moved further and further. I kept 5th place. Half the day was over, and I set myself the goal of finishing the first day at least in 5th place and still trying to keep a little gap with the previous ones.

There were 10 sudoku puzzles to solve in 50 minutes. In this round, there were 5 seemingly different sudoku puzzles, 2 of each. There were 10 different types, however. They simply gave the same sudoku puzzle with different rules for similar types. 1: Grey cells - Odd sudoku: The gray cells contain even numbers 2: Grey cells - Plus-10: The sum of the numbers in the gray cells in the group of gray cells is 10. 3: Lines - Palindrome: The numbers are the same both ways along the line 4: Lines - Sorted sudoku: The numbers along the line must be in either descending or ascending order. 5: Numbers - Outside sudoku: The number next to the box must be in the first three squares of the given line. 6: Numbers - Sum/Product: The number next to the box is either the sum or product of the first three numbers. 7: Dots - Kropki: In the case of a black dot, adjacent numbers differ from each other by 2x. In the case of a white dot, by 1. 8: Dots - Kropki calculative: In the case of a black dot, the sum/difference/product or quotient of the numbers in adjacent cells is 10, in the case of a white dot, by 5. 9: Circle - Big-Small: Circles are drawn at the intersections of 4 cells with some numbers inside. The numbers show the smallest and largest number in these 4 cells. The numbers cannot be repeated in these 4 cells. 10: Circle - Product: The numbers show the product of two numbers found in these 4 cells. The numbers cannot be repeated in these 4 cells. I was able to do everything except the 6th and 8th. In the case of the 8th, I was very close to the solution. More than half of the grid was already filled in. However, it was an extremely complex task that I struggled with for quite a while. Morinishi finished everything 10 minutes before the time limit. I didn't see the results after this round, but I believe Hideaki Jo from Japan passed me in this round.

8 sudokus had to be solved within 50 minutes. 1: Diagonal 2: Antichess: the same numbers cannot be placed within a chess move 3: Blackout sudoku: There is one black square in each row, column and box where you don't need to write a number, so each area has 8 different numbers (the numbers are 1-9, which can be used). 4: Equation sudoku: There must be a mathematical operation in the gray boxes that must be valid. 5: Toroidal Irregular: A special-shaped sudoku where the regions go over the edges of the sudoku board. 6: Killer sudoku: Small regions are drawn on the sudoku board, with a small number at the top, which is the sum of the numbers in the region. 7: VX sudoku: If there is a V between two cells, then the sum of the numbers in these cells is 5, if there is an X, then 10. All Vs and Xs are given. 8: Property: There are hints in some places on the edges (big, small, odd, even). These determine the nature of the first two squares. Small - 1234, Big - 5678, Odd - 1357, Even - 2468. The Sudoku was 8x8. When the time was up, 6 sudokus had been solved. All except Equation and Blackout. I almost finished Blackout. However, I managed to leave one square empty in Toroidal Jigsaw sudoku, so 0 points there too. After this round, Florian Kirch came to me from Germany and said that he had just succeeded in this round and had finished everything. So Florian also passed me, and Hideaki was already further than 50 points. So I was in 7th place. However, the ones behind did not pose much of a threat to me if I intend to solve normally in the future.

I had to solve 6 sudoku puzzles in 35 minutes, all of which have some rule related to diagonals. I like diagonals in themselves, but when I saw these types, I didn't expect anything. 1: Argyle: There are many diagonals drawn on the sudoku board, where numbers cannot be repeated. 2: Diagonal Unequal sign: Diagonally, inequality signs are shown in some places. And inequalities must be valid in these places. 3: Little killer: The sums of the numbers on the diagonals are shown along all diagonals. 4: Diagonal Skyscraper: All the numbers on the sudoku board are like skyscrapers, which hide each other if they are taller than the skyscraper next to them. The numbers on the edge of the board show how many skyscrapers are visible in a given direction. There were 2 numbers given next to each row, where one pointed in one diagonal direction and the other in the other. You had to decide which one pointed in which direction. 5: Diagonal Consecutive: If there are consecutive numbers diagonally next to each other, then a line was drawn there. 6: Windmill: There are 4 broken lines drawn on the board in a circle, which pass through the corners of the sudoku board in 2-3-4 squares respectively. The numbers must not be repeated in them (it is easier to get the competition instructions from the website and see what it looks like - like a windmill anyway). I solved in the same order as given, only I left the skyscraper last. When I finished, there were still 5 minutes left and no one had finished yet. The result was a round win and I significantly reduced the gap with Hideaki and definitely passed Florian.

Within 40 minutes, 8 very difficult classic sudokus had to be solved. 2 were left unsolved, but I was not far from finishing the 7th. The first 4 increased the gap, I got a few more points back from Hideaki, so the gap was still 16 points (which is less than the sudoku where I decided to leave one box empty). The following reached the semi-finals: Jakub Ondrousek, Janek Mrozowski - about 1 minute later Kota Morinishi - about 2 minutes later than the first Thomas Snyder - about 3 minutes later than the first Hideaki Jo - 5 minutes later than the first (5:02 to be exact) me - 5:18 later than the first and 16 seconds later than Hideaki Florian Kirch - I think about half a minute behind me Yuhei Kusui (Japan), who was 14th throughout the tournament and after the 8th round, but had great results in the last two rounds. etc... (Unknown names to me) 10th was 8 minutes later than the first.