LeetCode-36-Valid-Sudoku

class Solution {
public:
    bool isValidSudoku(vector<vector<char>>& board) {
        int used1[9][9]={0},used2[9][9]={0},used3[9][9]={0};
        for(int i=0;i<board.size();++i){
            for(int j=0;j<board[i].size();++j){
                if(board[i][j]!='.'){
                    int num=board[i][j]-'0'-1,k=i/3*3+j/3;
                    if(used1[i][num]||used2[j][num]||used3[k][num])
                        return false;
                    used1[i][num]=used2[j][num]=used3[k][num]=1;
                }
            }
        }
        return true;
    }
};