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.
本题是检验一张9X9的矩阵是否满足数独的特性。即里面存有数字或者‘.’,判断已有的数字是否符合九宫格的规则。思路是开辟三个9*9的bool，分别代表行row，列col，和子九宫subSudo，判断是否有非法数字，如果有就判断输出非法，否则一直进行到最后。都没有非法元素，那就输出true。时间：12ms。代码如下：
class Solution { public: bool isValidSudoku(vector<vector<char>>& board) { if (board.size() != 9) return false; bool row[9][9], col[9][9], subSudo[9][9]; memset(row, false, sizeof row); memset(col, false, sizeof col); memset(subSudo, false, sizeof subSudo); for (size_t i = 0; i < 9; ++i){ if (board[i].size() != 9) return false; for (size_t j = 0; j < 9; ++j){ if (board[i][j] == ‘.‘) continue; int c = board[i][j] - ‘1‘; if (row[i][c] || col[j][c] || subSudo[3 * (i / 3) + j / 3][c]) return false; row[i][c] = col[j][c] = subSudo[3 * (i / 3) + j / 3][c] = true; } } return true; } };
原文：http://www.cnblogs.com/Scorpio989/p/4580078.html