C++ Program to Check whether Graph is a 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.

```
/*
```

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

```
 */
```
```
#include <iostream>
```
```
#include <cstdio>
```
```
#include <stack>
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```
#include <list>
```
```
using namespace std;
```
```
/*
```
```
 * Class Declaration
```
```
 */
```
```
class Graph
```
```
{
```
```
    public:
```
```
        int V;
```
```
        list<int> *adj;
```
```
        Graph(int V);
```
```
        void addEdge(int v, int w);
```
```
};
```
```
/*
```
```
 * Constructor
```
```
 */
```
```
Graph::Graph(int V)
```
```
{
```
```
    this->V = V;
```
```
    adj = new list<int>[V];
```
```
}
```
```
/*
```
```
 * Adding Edge to Graph
```
```
 */
```
```
void Graph::addEdge(int v, int w)
```
```
{
```
```
    adj[v].push_back(w);
```
```
    adj[w].push_back(v);
```
```
}
```
```
/*
```
```
 * Class Bipartite Declaration
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```
 */
```
```
class Bipartite
```
```
{
```
```
    private:
```
```
        bool isBipartite;
```
```
        bool *color;
```
```
        bool *marked;
```
```
        int *edgeTo;
```
```
        stack<int> cycle;
```
```
    public:
```
```
        Bipartite(Graph G)
```
```
        {
```
```
            isBipartite = true;
```
```
            color = new bool [G.V];
```
```
            marked = new bool [G.V];
```
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            edgeTo = new int [G.V];
```

            for (int v = 0; v < G.V; v++)

```
            {
```
```
                if (!marked[v])
```
```
                {
```
```
                    color[v] = false;
```
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                    dfs(G, v);
```
```
                }
```
```
            }
```
```
        }
```
```
        /*
```
```
         * DFS
```
```
         */
```
```
        void dfs(Graph G, int v)
```
```
        {
```
```
            marked[v] = true;
```
```
            list<int>::iterator w;
```

            for (w = G.adj[v].begin(); w != G.adj[v].end(); w++)

```
            {
```
```
                if (!cycle.empty())
```
```
                    return;
```
```
                if (!marked[*w])
```
```
                {
```
```
                    edgeTo[*w] = v;
```

                    color[*w] = !color[v];

```
                    dfs(G, *w);
```
```
                }
```

                else if (color[*w] == color[v])

```
                {
```

                    isBipartite = false;

```
                    cycle.push(*w);
```

                    for (int x = v; x != *w; x = edgeTo[x])

```
                    {
```
```
                        cycle.push(x);
```
```
                    }
```
```
                    cycle.push(*w);
```
```
                }
```
```
            }
```
```
        }
```
```
        /* 
```

         * Returns true if graph is Bipartite

```
         */
```
```
        bool isBi()
```
```
        {
```
```
            return isBipartite;
```
```
        }
```
```
};
```
```
 
```
```
/*
```
```
 * Main Contains Menu
```
```
 */
```
```
int main()
```
```
{
```
```
    Graph g1(4);
```
```
    g1.addEdge(0, 1);
```
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    g1.addEdge(0, 3);
```
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    g1.addEdge(1, 0);
```
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    g1.addEdge(1, 2);
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    g1.addEdge(2, 1);
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    g1.addEdge(2, 3);
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    g1.addEdge(3, 2);
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    g1.addEdge(3, 0);
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```
    Bipartite b(g1);
```
```
    if (b.isBi())
```

        cout<<"The graph is Bipartite"<<endl;

```
    else
```

        cout<<"The graph is not Bipartite"<<endl;

```
}
```

$ g++ bipartite_dfs.cpp
$ a.out
The graph is Bipartite
 
 
------------------
(program exited with code: 1)
Press return to continue

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