C++ Program to Find Number of Cycles in a Graph

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This C++ Program Finds the Number of Cycles in a Graph.

Here is source code of the C++ Program to Find Number of Cycles in a Graph. The C++ program is successfully compiled and run on a Linux system. The program output is also shown below.

  1. /* 
  2.  * C++ Program to Find Number of Cycles in a Graph
  3.  */
  4. #include<iostream>
  5. #define SIZE 20
  6. using namespace std;
  7.  
  8. bool map[SIZE][SIZE], F;
  9. long long f[1 << SIZE][SIZE], res = 0;
  10. /* 
  11.  * Main: count the number of cycles in a graph
  12.  */
  13. int main()
  14. {
  15.     int n , m, i, j, k, l, x, y;
  16.     cout<<"Enter number of vertices: ";
  17.     cin>>n;
  18.     cout<<"Enter number of edges: ";
  19.     cin>>m;
  20.     for (i = 0; i < m; i++)
  21.     {
  22.         cout<<"Enter source vertex of an edge: ";
  23.         cin>>x;
  24.         cout<<"Enter destination vertex of an edge: ";
  25.         cin>>y;
  26.         x--;
  27.         y--;
  28.         if (x > y)
  29.            swap(x, y);
  30.         map[x][y] = map[y][x] = 1;
  31.         f[(1 << x) + (1 << y)][y] = 1;
  32.     }
  33.  
  34.     for (i = 7; i < (1 << n); i++)
  35.     {
  36.         F = 1;
  37.         for (j = 0; j < n; j++)
  38.         {
  39.             if (i & (1 << j) && f[i][j] == 0)
  40.             {
  41.                 if (F)
  42.                 {
  43.                     F = 0;
  44.                     k = j;
  45.                     continue;
  46.                 }
  47.                 for (l = k + 1; l < n; l++)
  48.                 {
  49.                     if (i & (1 << l) && map[j][l])
  50.                         f[i][j] += f[i - (1 << j)][l];
  51.                 }
  52.                 if (map[k][j])
  53.                     res += f[i][j];
  54.             }    
  55.         }
  56.     }
  57.     cout<<"Number of Cycles: "<<res/2<<endl;
  58.     return 0;
  59. }

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$ g++ cycles_graph.cpp
$ a.out
 
Enter number of vertices: 5
Enter number of edges: 8
Enter source vertex of an edge: 1
Enter destination vertex of an edge: 2
Enter source vertex of an edge: 1
Enter destination vertex of an edge: 5
Enter source vertex of an edge: 2
Enter destination vertex of an edge: 4
Enter source vertex of an edge: 2
Enter destination vertex of an edge: 3
Enter source vertex of an edge: 3
Enter destination vertex of an edge: 1
Enter source vertex of an edge: 4
Enter destination vertex of an edge: 3
Enter source vertex of an edge: 5
Enter destination vertex of an edge: 2
Enter source vertex of an edge: 5
Enter destination vertex of an edge: 1
Number of Cycles: 6
 
------------------
(program exited with code: 1)
Press return to continue

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn