Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules.
The Sudoku board could be partially filled, where empty cells are filled with the character
‘.‘.
A partially filled sudoku which is valid.
Note:
A valid Sudoku board (partially filled) is not necessarily solvable. Only the filled cells need to be validated.
算法思路：
逐行逐列判断行列是否有冲突，然后再逐块判断。
从网上看到有位大拿写的矩阵标记法，第二遍看继续亮瞎。不敢班门弄斧，然后上人家的算法吧。
代码如下：
1 public class Solution { 2 public boolean isValidSudoku(char[][] board) { 3 if(board == null || board.length != 9 || board[0].length != 9) return false; 4 boolean[][] row = new boolean[9][9]; 5 boolean[][] col = new boolean[9][9]; 6 boolean[][] matrix = new boolean[9][9]; 7 for(int i = 0; i < 9; i++){ 8 for(int j = 0; j < 9; j++){ 9 if(board[i][j] == ‘.‘) continue; 10 int n = board[i][j] - ‘1‘; 11 if(row[i][n] || col[j][n] || matrix[i - i % 3 + j / 3][n]){ 12 return false; 13 } 14 row[i][n] = col[j][n] = matrix[i - i % 3 + j / 3][n] = true; 15 16 } 17 } 18 return true; 19 } 20 }
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原文：http://www.cnblogs.com/huntfor/p/3901551.html
