As the game progesses, you may want to use notes. ![]() To highlight numbers, click a number that has aready been placed inside the sudoku puzzle. If not, the number will return to the outside and time will be added to your overall sudoku game time. If the number is correct, the sudoku tile will slide into its correct slot. To play 24/7 Sudoku, employ the basic object of the game by clicking an open space and either typing the number that belongs, or selecting it from the numbers on the side of the sudoku board. Every row, column, and 3x3 box in the sudoku board must contain the digits 1 through 9 only once! As the difficulty progresses, the sudoku game becomes harder, and you'll have to employ more advanced and strategic logic to solve the puzzles. ![]() The sudoku board is broken down into nine 3x3 squares. Sudoku is a brain challenging number game, played on a 9x9 sudoku board. Many thanks to Peter for posing questions and pushing me to dig a little deeper.Welcome to 24/7 Sudoku - the best in free, online sudoku games! 24/7 Sudoku offers all the difficulties a beginner or seasoned sudoku player will enjoy! This free sudoku website features hundreds of Easy Sudoku puzzles, Medium Sudoku puzzles, Hard Sudoku puzzles, and Expert Sudoku puzzles! 24/7 Sudoku is sure to keep you playing this great sudoku game all day, every day! It seems to me now that sometimes a little brute force is not only easier, but that it can be faster than a more elegant solution as well. Yes, but sometimes a little brute force is easier than figuring out how to do an elegant solution. I think his response summarizes this whole exercise for me quite well. When we were discussing how Peter had generated the graphs he used in his article, I remarked (tongue-in-cheek) that copying and pasting execution times into a spreadsheet sounded a lot like brute-force manual labour to me. The exact puzzle that required the original algorithm 91.06 seconds to solve took the modified version a mere 0.0079870224 seconds. you want more certainty about the maximum time required to solve a single puzzle), my money is still on the modified version. When solving many, randomly generated puzzles the original is slightly faster on average.īut when the task at hand involves more difficult Sudoku puzzles, or when you are operating under strict time constraints (i.e. My modified algorithm does not solve every Sudoku puzzle faster, as the title of my previous post implied. The original algorithm solves these random puzzles about fourteen percent quicker on average, but the distribution of execution times is more spread out as is evident from the much larger standard deviation and higher maximum.īased on these findings I have to admit I was wrong. This is in line with Peter’s earlier findings. This seems to indicate that most of these random puzzles are easier to solve save for a few extreme puzzles. For the same puzzles, my modified version required an average of 0.008 seconds per puzzle (124 puzzles per second) with a maximum execution time of merely 5.75 seconds.īoth these averages are far lower than those for the ninety-five difficult puzzles attempted earlier, but the maxima are orders of magnitude higher. Peter’s original algorithm required an average of 0.007 seconds per puzzle (142 puzzles per second) with a maximum execution time of 91.06 seconds. Overnight, one million random puzzles were attempted by the two competing algorithms (999.925 were actually solved). This allowed me to measure execution times more precisely. Secondly, I modified the code so that it uses the timeit module for measuring execution times. This is especially important since Peter’s experiments showed that long execution times (difficult puzzles) are rare but have an extreme impact a few puzzles taking more than a minute to solve. Otherwise one algorithm might, simply by virtue of some serious bad luck, end up with more difficult puzzles. To make this a fair competition, I made some slight modifications.įirstly, I had to ensure that both algorithms were solving the exact same random puzzles. The results were a little unexpected, but not very surprising. ![]() So I set out to make a more rigorous analysis of the relative strengths of our approaches using the method for generating random puzzles included in the original code. I had only compared the performance of the two algorithms based on the ninety-five difficult puzzles provided by Peter, but he was not convinced. So maybe I was jumping to conclusions a little early in the game.Īfter I posted my own modified version of Peter Norvig’s Sudoku Solver, Peter and I had some brief discussion about my results and conclusions. ![]() Solving Some Sudoku Puzzles Faster (I Stand Corrected)
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