sudoku

问题 I'm struggling with a backtracking algorithm to determine wether a Sudoku has a unique solution or if it has multiple Solutions. Here's the backtracking code i use: static boolean solve(int i, int j, int[][] cells) { if (i == 9) { i = 0; if (++j == 9) return true; } if (cells[i][j] != 0) // skip filled cells return solve(i+1,j,cells); for (int val = 1; val <= 9; ++val) { if (legal(i,j,val,cells)) { cells[i][j] = val; if (solve(i+1,j,cells)) return true; } } cells[i][j] = 0; // reset on

问题 I created a Sudoku Backtracking solver and it works just fine, but now i want to give out an error if the sudoku cant be solved because it isnt valid for example if this sudoku is given: http://img5.imageshack.us/img5/2241/sudokugq.jpg what can i do to make my solving method give out an error if it isnt solveable? I always end up with Zeros or stuck in a loop. public void solve( int row, int col ) throws Exception { // Throw an exception to stop the process if the puzzle is solved if( row > 8

问题 I was reading a question posted here: Sudoku algorithm in C# And one of the solutions posted was this piece of code. public static bool IsValid(int[] values) { int flag = 0; foreach (int value in values) { if (value != 0) { int bit = 1 << value; if ((flag & bit) != 0) return false; flag |= bit; } } return true; } The idea is that it will detect duplicates in the array of values; but I'm overwhelmed by how much I don't know. Can someone explain this to me? EDIT: Thanks everyone. So many great

问题 I was reading a question posted here: Sudoku algorithm in C# And one of the solutions posted was this piece of code. public static bool IsValid(int[] values) { int flag = 0; foreach (int value in values) { if (value != 0) { int bit = 1 << value; if ((flag & bit) != 0) return false; flag |= bit; } } return true; } The idea is that it will detect duplicates in the array of values; but I'm overwhelmed by how much I don't know. Can someone explain this to me? EDIT: Thanks everyone. So many great

问题 I'm hoping to optimize my backtracking algorithm for my Sudoku Solver. What it does now: The recursive solver function takes a sudoku puzzle with various given values. I will scour through all the empty slots in the puzzle, looking for the slot that has the least possibilities, and get the list of values. From the list of values, I will loop through it by placing one of the values from the list in the slot, and recursively solve it, until the entire grid is filled. This implementation still

问题 I'm trying to code a sudoku solver, and the way I attempted to do so was to have a 9x9 grid of pointers that hold the address of "set" objects that posses either the solution or valid possible values. I was able to go through the array with 2 for loops, through each column first and then going to the next row and repeating. However, I'm having a hard time imagining how I would designate which sub-grid (or box, block etc) a specific cell belongs to. My initial impression was to have if

问题 Is there an algorithm or way I can get initial state sudoku puzzles for a sudoku game. Preferably with the ability to have different levels of difficulty? 回答1: Basically there are two approaches. In both you need to have 2 solvers, a humanlike solver, which uses strategies performable by a human and a backtracking solver. With the first approach you generate a random complete solution and iteratively remove random cells solutions. Backtracking solver will make sure, that there still exist

问题 I have a problem with some part of my lisp code. It is a sudoku table generator. It works fine until this part: (loop for e in entries do (if (and (not (member e sub)) (not (member e col))) (progn (setq choices (nconc choices (list e))) (print choices))) (if (= (length choices) 1) (setq pick (car choices)) (if (not (= (length choices) 0)) (setq pick (nth (random (+ 0 (length choices))) choices)))) Basically, I am on a row x and a column y, and I need to insert an element. I watch the

问题 I'm trying to make a sudoku generator so I can make into a sudoku game and I've encountered a problem... I have successfully made a method which checks a certain cell and whether the number in it repeats in the same row, column or 3x3 square it belongs to but I have a problem with generating the numbers randomly and filling them in. Basically first I fill the first line with random numbers from 1-9 which only appear once in the line. My question is, is it possible to fill cell after cell with

问题 Hello I need help creating 9 sub arrays of 3x3 dimensions from a 9x9 array. I've seen that stackOverflow had a similar question already asked but unfortunately it was in c++. Can anyone point me in the right direction of how to create a a sub array. Edit: had aa similar changed to had a similar public static void Validate(final int[][] sudokuBoard) { int width = sudokuBoard[0].length; int height = sudokuBoard.length; for(int i = 0; i < width; i++) if(!IsValidRow(sudokuBoard, i, width)) {