See: https: //leetcode.com/problems/valid-sudoku/description/
class Solution {
public:
bool isValidSudoku(vector<vector<char>>& board) {
for(int i = 0; i < 9; i ++)
{
unordered_map<char, bool> m1; //check i_th row
unordered_map<char, bool> m2; //check i_th column
unordered_map<char, bool> m3; //check i_th subgrid
for(int j = 0; j < 9; j ++)
{
if(board[i][j] != '.')
{
if(m1[board[i][j]] == true)
return false;
m1[board[i][j]] = true;
}
if(board[j][i] != '.')
{
if(m2[board[j][i]] == true)
return false;
m2[board[j][i]] = true;
}
if(board[i/3*3+j/3][i%3*3+j%3] != '.')
{
if(m3[board[i/3*3+j/3][i%3*3+j%3]] == true)
return false;
m3[board[i/3*3+j/3][i%3*3+j%3]] = true;
}
}
}
return true;
}
};
Reference: http: //www.cnblogs.com/ganganloveu/p/4170632.html
