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  1. #include <vector>
  2. #include <iostream>
  3. using namespace std;
  4. class Solution {
  5. private:
  6.     bool solve(vector<vector<char>> &board){   
  7.         for(int i=0; i<9; i++){
  8.             for(int j=0; j<9; j++){
  9.                 if(board[i][j] == '.'){
  10.                     for(char ch='1'; ch<='9'; ch++){
  11.                         if(isValid(board, i, j, ch)){
  12.                             board[i][j] = ch;
  13.                             if(solve(board))
  14.                                 return true;
  15.                             else{
  16.                                 board[i][j] = '.';   
  17.                             }
  18.                         }
  19.                     }
  20.                     return false;
  21.                 }
  22.  
  23.             }
  24.         }
  25.         return true;
  26.     }
  27.  
  28.     bool isValid(vector<vector<char>>& board, int row, int col, char ch){
  29.         for(int i=0; i<9; i++){
  30.             if(board[row][i] == ch) return false;
  31.             if(board[i][col] == ch) return false;
  32.             if(board[3*(row/3) + i/3][3*(col/3) + i%3] == ch) return false;
  33.         }
  34.  
  35.         return true;
  36.     }
  37.  
  38. public:
  39.     void solveSudoku(vector<vector<char>>& board) {
  40.         solve(board);
  41.     }
  42. };
  43.  
  44. int main() {
  45.     Solution solution;
  46.     vector<vector<char>> board = {
  47.         {'5', '3', '.', '.', '7', '.', '.', '.', '.'},
  48.         {'6', '.', '.', '1', '9', '5', '.', '.', '.'},
  49.         {'.', '9', '8', '.', '.', '.', '.', '6', '.'},
  50.         {'8', '.', '.', '.', '6', '.', '.', '.', '3'},
  51.         {'4', '.', '.', '8', '.', '3', '.', '.', '1'},
  52.         {'7', '.', '.', '.', '2', '.', '.', '.', '6'},
  53.         {'.', '6', '.', '.', '.', '.', '2', '8', '.'},
  54.         {'.', '.', '.', '4', '1', '9', '.', '.', '5'},
  55.         {'.', '.', '.', '.', '8', '.', '.', '7', '9'}
  56.     };
  57.     solution.solveSudoku(board);
  58.     for (const auto& row : board) {
  59.         for (const auto& cell : row) {
  60.             cout << cell << " ";
  61.         }
  62.         cout << endl;
  63.     }
  64.  
  65.     return 0;
  66. }
  67.  
  68.  
Success #stdin #stdout 0.01s 5280KB
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stdin
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Standard input is empty
stdout
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5 3 4 6 7 8 9 1 2 
6 7 2 1 9 5 3 4 8 
1 9 8 3 4 2 5 6 7 
8 5 9 7 6 1 4 2 3 
4 2 6 8 5 3 7 9 1 
7 1 3 9 2 4 8 5 6 
9 6 1 5 3 7 2 8 4 
2 8 7 4 1 9 6 3 5 
3 4 5 2 8 6 1 7 9
https://ideone.com/1Er26m
language:
C++14 (gcc 8.3)
created:
174 days ago
visibility:
public

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