leetcode-----36. 有效的数独

• 链接：https://leetcode-cn.com/problems/valid-sudoku/

代码

class Solution {
public:
    bool isValidSudoku(vector<vector<char>>& board) {
        bool st[9];

        // 行
        for (int i = 0; i < 9; ++i) {
            memset(st, 0, sizeof st);

            for (int j = 0; j < 9; ++j) {
                if (board[i][j] != '.') {
                    int t = board[i][j] - '1';
                    if (st[t]) return false;
                    st[t] = true;
                }
            }
        }

        // 列
        for (int i = 0; i < 9; ++i) {
            memset(st, 0, sizeof st);
            for (int j = 0; j < 9; ++j) {
                if (board[j][i] != '.') {
                    int t = board[j][i] - '1';
                    if (st[t]) return false;
                    st[t] = true;
                }
            }
        }

        // 小方格
        for (int i = 0; i < 9; i += 3) {
            for (int j = 0; j < 9; j += 3) {
                memset(st, 0, sizeof st);
                for (int x = 0; x < 3; ++x) {
                    for (int y = 0; y < 3; ++y) {
                        if (board[i + x][j + y] != '.') {
                            int t = board[i + x][j + y] - '1';
                            if (st[t]) return false;
                            st[t] = true;
                        }
                    }
                }
            }
        }
        return true; 
    }
};