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  1. #include <iostream>
  2. #include <iomanip>
  3. #include <climits>
  4. #include <algorithm>
  5. #include <vector>
  6. #include <map>
  7. #include <set>
  8. #include <cmath>
  9. using namespace std;
  10.  
  11. long long mod = 1e9 + 7;
  12.  
  13. #define fast_io() ios::sync_with_stdio(false); cin.tie(nullptr);
  14.  
  15. const int N = 9;
  16. int board[10][10];
  17. bool check(int row, int col, int x){
  18.     // kiểm tra hàng
  19.     for (int i = 0; i < N; i++){
  20.         if (board[row][i] == x){
  21.             return false;
  22.         }
  23.     }
  24.     // kiểm tra cột
  25.     for (int i = 0; i < N; i++){
  26.         if (board[i][col] == x){
  27.             return false;
  28.         }
  29.     }
  30.     // kiểm tra trong ô 3x3
  31.     int startRow = row - row % 3, startCol = col - col % 3;
  32.     for (int i = startRow; i < startRow + 3; i++){
  33.         for (int j = startCol; j < startCol + 3; j++){
  34.             if (board[i][j] == x){
  35.                 return false;
  36.             }
  37.         }
  38.     }
  39.     return true;
  40. }
  41.  
  42. bool BackTrack(int row, int col){
  43.     if (row == N - 1 && col == N){
  44.         return true;
  45.     }
  46.     if (col == N){
  47.         row++;
  48.         col = 0;
  49.     }
  50.     if (board[row][col] != 0){
  51.         return BackTrack(row, col + 1);
  52.     }
  53.     else{
  54.         for (int i = 1; i <= N; i++){
  55.             if (check(row, col, i)){
  56.                 board[row][col] = i;
  57.                 if (BackTrack(row, col + 1)){
  58.                     return true;
  59.                 }
  60.             }
  61.             board[row][col] = 0;
  62.         }
  63.         return false;
  64.     }
  65. }
  66. int main(){
  67.     for (int i = 0; i < N; i++){
  68.         for (int j = 0; j < N; j++){
  69.             cin >> board[i][j];
  70.         }
  71.     }
  72.     if (BackTrack(0, 0)){
  73.         cout << "28tech" << endl;
  74.     }
  75.     else cout << "29tech" << endl;
  76.     return 0;
  77. }
Success #stdin #stdout 0.01s 5328KB
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28tech
https://ideone.com/limYGw
language:
C++ (gcc 8.3)
created:
13 hours ago
visibility:
public

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