C++ Program to Implement Disjoint Set Data Structure

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This C++ program implements the Disjoint Set data structure. It is a data structure that keeps track of a set of elements partitioned into a number of disjoint (nonoverlapping) subsets.

Here is the source code of the C++ program to display the sum of data subsets the data strucure has been partitioned in. This C++ program is successfully compiled and run on DevCpp, a C++ compiler. The program output is given below.

  1. /*
  2. * C++ Program to Implement Disjoint Set Data Structure
  3.  */
  4. #include <iostream>
  5. #include <cstdio>
  6. #include <vector>
  7. #include <algorithm>
  8. using namespace std;
  9. #define INF 1000000000
  10.  
  11. typedef pair<int ,int> ii;
  12. typedef vector <int> vi;
  13.  
  14. vector <pair<int ,ii> > edges;
  15. vi pset;
  16.  
  17. void init(int N)
  18. {
  19.     pset.assign(N, 0);
  20.     for(int i = 0; i < N; i++)
  21.     {
  22.         pset[i] = i;
  23.     }
  24. }
  25.  
  26. int find_set(int i)
  27. {
  28.     if(pset[i] == i)
  29.     {
  30.         return pset[i];
  31.     }
  32.     return pset[i] = find_set(pset[i]);
  33. }
  34. bool issameset (int i, int j)
  35. {
  36.     return find_set(i) == find_set(j);
  37. }
  38. void joinset(int i, int j)
  39. {
  40.     pset[find_set(i)] = find_set(j);
  41. }
  42. int main()
  43. {
  44.     int n, m, a, b, dist, t;
  45.     cin>>t;
  46.     while(t--)
  47.     {
  48.         cin>>n>>m;
  49.         init(n);
  50.         edges.clear();
  51.         for (int i = 0; i < m; i++)
  52.         {
  53.             cin>>a>>b>>dist;
  54.             a--,b--;
  55.             ii tmp = make_pair(a, b);
  56.             edges.push_back(make_pair(dist, tmp));
  57.         }
  58.         sort(edges.rbegin(),edges.rend());
  59.         int sum = 0;
  60.         for(int i = 0; i < edges.size(); i++)
  61.         {
  62.             if (!issameset (edges[i].second.first, edges[i].second.second))
  63.             {
  64.                joinset(edges[i].second.first, edges[i].second.second);
  65.             }
  66.             else sum += edges[i].first;
  67.         }
  68.         cout<<sum;
  69.     }
  70.     cin>>t;
  71.     getch();
  72. }

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Output
enter the number of sets to be  computed
1
enter the number of disjoint sets and the number of rows
2
3
enter the start and end vertices alongwith weight of edge
1
1
2
enter the start and end vertices alongwith weight of edge
1
1
3
enter the start and end vertices alongwith weight of edge
1
1
4
Sum is:9

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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