leetcode 36. Valid Sudoku

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.

2.思路 

class Solution {
public:
    bool check(vector<int> &a , char c)
    {
        if(c == '.') return true;
        if(a[c-'0'] == 0){
            a[c-'0']++;
            return true;
        }
        else return false;
    }
    bool isValidSudoku(vector<vector<char>>& board) {
        vector<int> row_valid(10);
        vector<int> col_valid(10);
        vector<vector<int> > sub_valid(10,vector<int>(10));
        for(int i = 0;i<9;i++){
            row_valid.assign(10, 0);
            col_valid.assign(10, 0);
            for(int j = 0;j<9;j++){
                if(!check(row_valid,board[i][j])) return false;
                if(!check(col_valid,board[j][i])) return false;
                if(!check(sub_valid[(i/3)*3+j/3],board[i][j])) return false;
            }
        }
        return true;
    }
};