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  1. #include <iostream>
  2. using namespace std;
  3. #define SQUARE_SIZE 9
  4.  
  5. int anyLine = 0;
  6. int currLine = 0;
  7. int numSolutions = 0;
  8.  
  9.  
  10. // swap two values in the square.
  11. void swap (int arr[], int idxa, int idxb)
  12. {
  13.   int tmp = arr[idxa];
  14.   arr[idxa] = arr[idxb];
  15.   arr[idxb] = tmp;
  16. }
  17.  
  18.  void printArray(int arr[])
  19.  {
  20.    for (int i = 0; i < SQUARE_SIZE; i++)
  21.   {
  22.     cout << arr[i] << " ";
  23.     if((i+1) % 3 == 0)
  24.         cout << endl;
  25.   }
  26.   cout << endl;
  27.  }
  28.  
  29. // this function tests to see if we have a "good" arrangment of numbers            
  30. //   i.e the sum of each row, colum and diagonal is equal
  31.  
  32. bool checkArr(int arr[])
  33. {
  34.   anyLine = arr[0] + arr[1] + arr[2];
  35.   currLine = 0;
  36.   for (int i = 0; i < SQUARE_SIZE; i++)
  37.   {
  38.     currLine += arr[i];
  39.     if((i+1) % 3 == 0)
  40.     {
  41.         if (currLine != anyLine)
  42.         return false;
  43.         currLine = 0;
  44.     }
  45.   }
  46.   // check vertically
  47.   for (int col = 0; col <3; col++)
  48.  {
  49.     for (int row = 0; row <3; row++)
  50.     {
  51.         currLine += arr[col + 3 * row];
  52.     }
  53.     if (currLine != anyLine)
  54.         return false;
  55.         currLine = 0;
  56.   }
  57.  
  58.   // check the diagonals
  59.   if ((arr[2] + arr[4] + arr[6]) != anyLine)
  60.     return false;
  61.  
  62.   if ((arr[0] + arr[4] + arr[8]) != anyLine)
  63.     return false;
  64.  
  65.   return true;
  66.  }
  67.  
  68.  void solve(int arr[], int pos)
  69.  {
  70.  
  71.   if (pos == 8)
  72.  {
  73.  
  74.  if (checkArr(arr))
  75.  {
  76.     printArray(arr);
  77.     numSolutions++;
  78.  }
  79.  
  80. }else
  81. {
  82. for (int i = pos ; i < 9; i++)
  83. { 
  84.  
  85.     /*if (checkArr(arr))
  86.     {
  87.         printArray(arr);
  88.         numSolutions++;
  89.     }*/
  90.  
  91.     //if (i == pos) continue;
  92.  
  93.        swap(arr,pos,i);
  94.        solve(arr,pos +1);
  95.        swap(arr,pos,i);
  96.  
  97.     }
  98.   }
  99. }
  100.  
  101. int main()
  102. {
  103.  
  104. int arr[SQUARE_SIZE]= { 1,2,3,4,5,6,7,8,9 };
  105.  
  106. solve(arr,0);
  107. cout << "number of solutions is: " << numSolutions<< endl;
  108.  
  109. return 0;
  110. }
  111.  
Success #stdin #stdout 0.01s 3140KB
comments (?)
stdin
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Standard input is empty
stdout
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2 7 6 
9 5 1 
4 3 8 

2 9 4 
7 5 3 
6 1 8 

4 3 8 
9 5 1 
2 7 6 

4 9 2 
3 5 7 
8 1 6 

6 1 8 
7 5 3 
2 9 4 

6 7 2 
1 5 9 
8 3 4 

8 3 4 
1 5 9 
6 7 2 

8 1 6 
3 5 7 
4 9 2 

number of solutions is: 8
https://ideone.com/IW8jfD
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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