标签：
https://leetcode.com/problems/sudoku-solver/
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.
dfs回朔。。
class Solution {
public:
static const int N = 9;
int cnt;
struct Node {
int x, y;
Node() {}
Node(int i, int j) :x(i), y(j) {}
}st[N * N];
void solveSudoku(vector<vector<char>>& board) {
cnt = 0;
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++) {
if (board[i][j] == ‘.‘) {
st[cnt++] = Node(i, j);
}
}
}
dfs(board, 0);
}
bool dfs(vector<vector<char>>& board, int t) {
if (t == cnt) return true;
for (int i = 1; i <= N; i++) {
int x = st[t].x, y = st[t].y;
if (isOk(board, x, y, i + ‘0‘)) {
board[x][y] = i + ‘0‘;
if (dfs(board, t + 1)) return true;
board[x][y] = ‘.‘;
}
}
return false;
}
bool isOk(vector<vector<char>>& board, int x, int y, char ch) {
for (int i = 0; i < N; i++) {
if (board[x][i] == ch || board[i][y] == ch) return false;
}
for (int i = x / 3 * 3; i <= x / 3 * 3 + 2; i++) {
for (int j = y / 3 * 3; j <= y / 3 * 3 + 2; j++) {
if (board[i][j] == ch) return false;
}
}
return true;
}
};
标签：
原文地址：http://www.cnblogs.com/GadyPu/p/5040166.html
