LeetCode 37. Sudoku Solver

Solution1：
转载自花花酱：http://zxi.mytechroad.com/blog/searching/leetcode-37-sudoku-solver/
与之前的DFS套路题不大一样，注意！

class Solution {
public:void solveSudoku(vector<vector<char>>& board) {rows_ = vector<vector<int>>(9, vector<int>(10));cols_ = vector<vector<int>>(9, vector<int>(10));boxes_ = vector<vector<int>>(9, vector<int>(10));//预先设置剪枝条件for(int i = 0; i < 9; i++)for(int j = 0; j < 9; j++) {const char c = board[i][j];                if ( c != '.') {int n = c - '0';                    int bx = i / 3;int by = j / 3;rows_[i][n] = 1;cols_[j][n] = 1;boxes_[bx * 3 + by][n] = 1;}}fill(board, 0, 0);}private:vector<vector<int>> rows_, cols_, boxes_;bool fill(vector<vector<char>>& board, int x, int y) {if (x == 9)return true;int ny = (y + 1) % 9;int nx = (ny == 0) ? x + 1 : x;if (board[x][y] != '.') return fill(board, nx, ny);for (int i = 1; i <= 9; i++) {int bx = x / 3;int by = y / 3;int box_key = bx * 3 + by;if (!rows_[x][i] && !cols_[y][i] && !boxes_[box_key][i]) {rows_[x][i] = 1;cols_[y][i] = 1;boxes_[box_key][i] = 1;board[x][y] = i + '0';if (fill(board, nx, ny)) return true;board[x][y] = '.';boxes_[box_key][i] = 0;cols_[y][i] = 0;rows_[x][i] = 0;}}return false;}
};

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【DFS + backtrack】LeetCode 37. Sudoku Solver

LeetCode 37. Sudoku Solver

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