LeetCode:Valid Sudoku

Valid Sudoku

Total Accepted: 60134  Total Submissions: 206702  Difficulty: Easy

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.

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思路：

1.定义3个9*9的bool数组rows[9][9],cols[9][9],boxs[9][9]，分别表示9行、9列、9格中1-9数字的出现情况；

2.逐个扫描，当num = board[i][j]这个数在rows[i][num],cols[j][num],boxs[k][num]中任何一个出现过时，

说明重复，返回false；

3.最后返回true。

code:

class Solution {
public:
    bool isValidSudoku(vector<vector<char>>& board) {
        bool rows[9][9] = {false};
        bool cols[9][9] = {false};
        bool boxs[9][9] = {false};
        
        for(int i=0;i<board.size();i++)
        for(int j=0;j<board[0].size();j++) {
            if(board[i][j] != '.') {
                int num = board[i][j] - '0' - 1;
                int k = i/3 * 3 + j/3;
                if(rows[i][num] || cols[j][num] || boxs[k][num])
                    return false;
                rows[i][num] = cols[j][num] = boxs[k][num] = true;
            }
        }
        return true;
    }
};