C++ Program to Check whether a Graph is Bipartite using DFS

This C++ Program checks whether Graph is a Bipartite using DFS

Here is source code of the C++ Program to check whether Graph is a Bipartite using DFS. The C++ program is successfully compiled and run on a Linux system. The program output is also shown below.

  1. /*
  2.  * C++ Program to Check whether Graph is a Bipartite using DFS
  3.  */
  4. #include <iostream>
  5. #include <cstdio>
  6. #include <stack>
  7. #include <list>
  8. using namespace std;
  9. /*
  10.  * Class Declaration
  11.  */
  12. class Graph
  13. {
  14.     public:
  15.         int V;
  16.         list<int> *adj;
  17.         Graph(int V);
  18.         void addEdge(int v, int w);
  19. };
  20. /*
  21.  * Constructor
  22.  */
  23. Graph::Graph(int V)
  24. {
  25.     this->V = V;
  26.     adj = new list<int>[V];
  27. }
  28. /*
  29.  * Adding Edge to Graph
  30.  */
  31. void Graph::addEdge(int v, int w)
  32. {
  33.     adj[v].push_back(w);
  34.     adj[w].push_back(v);
  35. }
  36. /*
  37.  * Class Bipartite Declaration
  38.  */
  39. class Bipartite
  40. {
  41.     private:
  42.         bool isBipartite;
  43.         bool *color;
  44.         bool *marked;
  45.         int *edgeTo;
  46.         stack<int> cycle;
  47.     public:
  48.         Bipartite(Graph G)
  49.         {
  50.             isBipartite = true;
  51.             color = new bool [G.V];
  52.             marked = new bool [G.V];
  53.             edgeTo = new int [G.V];
  54.             for (int v = 0; v < G.V; v++)
  55.             {
  56.                 if (!marked[v])
  57.                 {
  58.                     color[v] = false;
  59.                     dfs(G, v);
  60.                 }
  61.             }
  62.         }
  63.         /*
  64.          * DFS
  65.          */
  66.         void dfs(Graph G, int v)
  67.         {
  68.             marked[v] = true;
  69.             list<int>::iterator w;
  70.             for (w = G.adj[v].begin(); w != G.adj[v].end(); w++)
  71.             {
  72.                 if (!cycle.empty())
  73.                     return;
  74.                 if (!marked[*w])
  75.                 {
  76.                     edgeTo[*w] = v;
  77.                     color[*w] = !color[v];
  78.                     dfs(G, *w);
  79.                 }
  80.                 else if (color[*w] == color[v])
  81.                 {
  82.                     isBipartite = false;
  83.                     cycle.push(*w);
  84.                     for (int x = v; x != *w; x = edgeTo[x])
  85.                     {
  86.                         cycle.push(x);
  87.                     }
  88.                     cycle.push(*w);
  89.                 }
  90.             }
  91.         }
  92.         /* 
  93.          * Returns true if graph is Bipartite
  94.          */
  95.         bool isBi()
  96.         {
  97.             return isBipartite;
  98.         }
  99. };
  100.  
  101. /*
  102.  * Main Contains Menu
  103.  */
  104. int main()
  105. {
  106.     Graph g1(4);
  107.     g1.addEdge(0, 1);
  108.     g1.addEdge(0, 3);
  109.     g1.addEdge(1, 0);
  110.     g1.addEdge(1, 2);
  111.     g1.addEdge(2, 1);
  112.     g1.addEdge(2, 3);
  113.     g1.addEdge(3, 2);
  114.     g1.addEdge(3, 0);
  115.     Bipartite b(g1);
  116.     if (b.isBi())
  117.         cout<<"The graph is Bipartite"<<endl;
  118.     else
  119.         cout<<"The graph is not Bipartite"<<endl;
  120. }

$ g++ bipartite_dfs.cpp
$ a.out
The graph is Bipartite
 
 
------------------
(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 lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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