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  1. #include <iostream>
  2.  
  3. struct Matrix
  4. {
  5.     int data[9];
  6.     // indices
  7.     // 0 1 2
  8.     // 3 4 5
  9.     // 6 7 8
  10. };
  11.  
  12. int sumOfLine(Matrix& m, int lineNo)   // 0, 1 or 2
  13. {
  14.     return m.data[3*lineNo + 0] + m.data[3*lineNo + 1] + m.data[3*lineNo + 1];
  15. }
  16.  
  17. int sumOfColumn(Matrix& m, int columnNo) // 0, 1 or 2
  18. {
  19.     return m.data[columnNo + 3*0] + m.data[columnNo + 3*1] + m.data[columnNo + 3*2];
  20. }
  21.  
  22. int sumOfForwardDiag(Matrix& m)
  23. {
  24.     return m.data[6] + m.data[4] + m.data[2];
  25. }
  26.  
  27. int sumOfBackwardDiag(Matrix& m)
  28. {
  29.     return m.data[0] + m.data[4] + m.data[8];
  30. }
  31.  
  32. bool isMagicSquare(Matrix& m)
  33. {
  34.     bool isMagicSquare = true;
  35.     int targetSum = sumOfLine(m, 0);
  36.     for(int i=0; i<3; i++)
  37.     {
  38.         if(sumOfLine(m, i) != targetSum)
  39.         {
  40.             isMagicSquare = false;
  41.         }
  42.     }
  43.  
  44.     for(int i=0; i<3; i++)
  45.     {
  46.         if(sumOfColumn(m, i) != targetSum)
  47.         {
  48.             isMagicSquare = false;
  49.         }
  50.     }
  51.  
  52.     if(sumOfForwardDiag(m) != targetSum)
  53.         isMagicSquare = false;
  54.  
  55.     if(sumOfBackwardDiag(m) != targetSum)
  56.         isMagicSquare = false;
  57.  
  58.     return isMagicSquare;
  59. }
  60.  
  61. int main(int argc, char* argv[])
  62. {
  63.     Matrix m1 = { 0, 1, 2, 3, 4, 5, 6, 7, 8 };
  64.     Matrix m2 = { 1, 1, 1, 1, 1, 1, 1, 1, 1 };
  65.  
  66.     std::cout << "m1 is magic: " << isMagicSquare(m1) << std::endl;
  67.     std::cout << "m2 is magic: " << isMagicSquare(m2) << std::endl;
  68.  
  69.     return 0;
  70. }
Success #stdin #stdout 0s 2852KB
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Standard input is empty
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m1 is magic: 0
m2 is magic: 1
https://ideone.com/neTN7a
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
public

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