【leetcode】36. Valid Sudoku 给定的数独表格是否是满足规则的

1. 题目

Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules.

The Sudoku board could be partially filled, where empty cells are filled with the character '.'.

A partially filled sudoku which is valid.

Note:
A valid Sudoku board (partially filled) is not necessarily solvable. Only the filled cells need to be validated.

2. 思路

需要校验横、竖、方三个点，一共有27个9位向量。
将每一个点填入对一个的三个方形的标记数组中，如果已经填入过说明冲突了，就返回false。

3. 代码

class Solution {
public:
    // 横竖方一共有27种需要验证1-9的独立性, 遍历一次填入这27个向量里, 如果已有则证明重复
    bool isValidSudoku(vector<vector<char>>& board) {
        int exist[27][9];
        bzero(exist, sizeof(exist));
        for (int i = 0; i < board.size(); i++) {
            vector<char>& v = board[i];
            for (int j = 0; j < v.size(); j++) {
                char ch = v[j];
                int chv = ch - '1';
                if (ch == '.') continue;
                int k1;
                // i行
                k1 = i;
                //cout << "row i=" << i << " j=" << j << " k1=" << k1 << " exist=" << exist[k1][chv] << endl;
                if (exist[k1][chv] != 0) return false;
                exist[k1][chv] = 1;
                
                // j列
                k1 = 9 + j;
                //cout << "col i=" << i << " j=" << j << " k1=" << k1 << " exist=" << exist[k1][chv] << endl;
                if (exist[k1][chv] != 0) return false;
                exist[k1][chv] = 1;
                
                // 方形
                k1 = 18 + (i / 3) * 3 + j / 3;
                //cout << "squ i=" << i << " j=" << j << " k1=" << k1 << " exist=" << exist[k1][chv] << endl;
                if (exist[k1][chv] != 0) return false;
                exist[k1][chv] = 1;
            }
        }
        return true;
    }
};