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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.  
  14. const int N = 9;
  15. int board[10][10];
  16. bool check(int row, int col, int x){
  17.     // kiểm tra hàng
  18.     for (int i = 0; i < N; i++){
  19.         if (board[row][i] == x){
  20.             return false;
  21.         }
  22.     }
  23.     // kiểm tra cột
  24.     for (int i = 0; i < N; i++){
  25.         if (board[i][col] == x){
  26.             return false;
  27.         }
  28.     }
  29.     // kiểm tra trong ô 3x3
  30.     int startRow = row - row % 3, startCol = col - col % 3;
  31.     for (int i = startRow; i < startRow + 3; i++){
  32.         for (int j = startCol; j < startCol + 3; j++){
  33.             if (board[i][j] == x){
  34.                 return false;
  35.             }
  36.         }
  37.     }
  38.     return true;
  39. }
  40.  
  41. bool BackTrack(int row, int col){
  42.     if (row == N - 1 && col == N){
  43.         return true;
  44.     }
  45.     if (col == N){
  46.         row++;
  47.         col = 0;
  48.     }
  49.     if (board[row][col] != 0){
  50.         return BackTrack(row, col + 1);
  51.     }
  52.     else{
  53.         for (int i = 1; i <= N; i++){
  54.             if (check(row, col, i)){
  55.                 board[row][col] = i;
  56.                 if (BackTrack(row, col + 1)){
  57.                     return true;
  58.                 }
  59.             }
  60.             board[row][col] = 0;
  61.         }
  62.         return false;
  63.     }
  64. }
  65. int main(){
  66.     for (int i = 0; i < N; i++){
  67.         for (int j = 0; j < N; j++){
  68.             cin >> board[i][j];
  69.         }
  70.     }
  71.     if (BackTrack(0, 0)){
  72.         cout << "28tech" << endl;
  73.     }
  74.     else cout << "29tech" << endl;
  75.     return 0;
  76. }
Success #stdin #stdout 0.01s 5272KB
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28tech
https://ideone.com/mKYXpg
language:
C++ (gcc 8.3)
created:
13 hours ago
visibility:
public

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