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| class Solution {
public:
void solveSudoku(vector<vector<char>>& board) {
solveSudoku1(board, 0, 0);
}
bool solveSudoku1(vector<vector<char>>& board, int i, int j) {
if (i>=9||j>=9) return true;
if (board[i][j]=='.') {
vector<bool> used_numbers(9);
for (int k=0;k<9;k++) {
if (board[i][k]!='.') {
used_numbers[board[i][k]-'1']=true;
}
}
for (int k=0;k<9;k++) {
if (board[k][j]!='.') {
used_numbers[board[k][j]-'1']=true;
}
}
int grid_i = i / 3;
int grid_j = j / 3;
for (int m=3*grid_i;m<3+3*grid_i;m++) {
for (int n=3*grid_j;n<3+3*grid_j;n++) {
if (board[m][n]!='.') {
used_numbers[board[m][n]-'1']=true;
}
}
}
for (int ii=0;ii<9;ii++) {
if (used_numbers[ii]==false) {
board[i][j] = ii+'1';
if (solveSudoku1(board, i+(j+1)/9, (j+1)%9)) {
return true;
}
}
}
board[i][j] = '.';
return false;
}else{
return solveSudoku1(board, i+(j+1)/9, (j+1)%9);
}
}
};
|