标签：style http color os io ar for div 问题
Write a program to solve a Sudoku puzzle by filling the empty cells.
Empty cells are indicated by the character ‘.‘.
You may assume that there will be only one unique solution.
A sudoku puzzle...
...and its solution numbers marked in red.
题意：填充数独，返回是否填充成功
思路：dfs
找一个还没填充的位置，尝试填写0-9其中的一个数字，判断是否理。
如果合理，则可以转移到一个同样子问题，所以可以采用递归的方式实现。
bool solveSudoku(vector<vector<char> >&board)
返回是否成功填充当前状态为 board的数独
bool isValid(const vector<vector<char> >&board, int x, int y){
//检查行
for(int j = 0; j < 9; ++j) if(j != y && board[x][j] == board[x][y]) return false;
//检查列
for(int i = 0; i < 9; ++i) if(i != x && board[i][y] == board[x][y]) return false;
//检查小方块
for(int i = 0; i < 3; ++i)
for(int j = 0; j < 3; ++j){
if(!(x/3 * 3 + i == x && y /3 * 3 + j == y) && board[x/3 * 3 + i][y /3 * 3 + j] == board[x][y]) return false;
}
return true;
}
bool solveSudoku(vector<vector<char> >&board)
{
for(int i = 0; i < 9; ++i){
for(int j = 0; j < 9; ++j){
if(board[i][j] == '.'){
for(int k = 0; k < 9; ++k){
board[i][j] = k + '1' ;
if(isValid(board, i, j) && solveSudoku(board)) return true;
board[i][j] = '.';
}
return false;
}
}
}
return true; //漏写了这句，WA了好多次
}Leetcode dfs Binary Tree Postorder Traversal II
标签：style http color os io ar for div 问题
原文地址：http://blog.csdn.net/zhengsenlie/article/details/39104347
