36. Valid Sudoku

题目链接

https://leetcode.com/problems/valid-sudoku/

解题思路

直接看代码。

代码

class Solution {
public:
    bool isValidSudoku(vector<vector<char>>& board) {
        vector<bool> tag(10, false);
        //每3*3格子判断
        for (int i = 0; i < 9; i += 3) {
            for (int j = 0; j < 9; j += 3) {
                zero(tag);
                for (int a = i + 2; a >= i; --a) {
                    for (int b = j + 2; b >= j; --b) {
                        if (board[a][b] != '.') {
                            if (tag[board[a][b] - '0']) {
                                return false;
                            } else {
                                tag[board[a][b] - '0'] = true;
                            }
                        }
                    }
                }
            }
        }

        //每行的格子判断
        for (int i = 0; i < 9; i++) {
            zero(tag);
            for (int j = 0; j < 9; j++) {
                if (board[i][j] != '.') {
                    if (tag[board[i][j] - '0']) {
                        return false;
                    } else {
                        tag[board[i][j] - '0'] = true;
                    }
                }
            }
        }

        //每列的格子判断
        for (int i = 0; i < 9; i++) {
            zero(tag);
            for (int j = 0; j < 9; j++) {
                if (board[j][i] != '.') {
                    if (tag[board[j][i] - '0']) {
                        return false;
                    } else {
                        tag[board[j][i] - '0'] = true;
                    }
                }
            }
        }
        return true;
    }

    void zero(vector<bool> &v) {
        for (int k = 0; k < v.size(); ++k) {
            v[k] = false;
        }
    }
};