What is a bipartite graph?

#include <iostream> 
#include <queue> 
#define V 4 
using namespace std; 
// This function returns true if graph 
// G[V][V] is Bipartite, else false 
bool isBipartite(int G[][V], int src) 
{ 
	// Create a color array to store colors 
	// assigned to all veritces. Vertex 
	// number is used as index in this array. 
	// The value '-1' of colorArr[i] 
	// is used to indicate that no color 
	// is assigned to vertex 'i'. The value 1 
	// is used to indicate first color 
	// is assigned and value 0 indicates 
	// second color is assigned. 
	int colorArr[V]; 
	for (int i = 0; i < V; ++i) 
		colorArr[i] = -1; 
	// Assign first color to source 
	colorArr[src] = 1; 
	// Create a queue (FIFO) of vertex 
	// numbers and enqueue source vertex 
	// for BFS traversal 
	queue <int> q; 
	q.push(src); 
	// Run while there are vertices 
	// in queue (Similar to BFS) 
	while (!q.empty()) 
	{ 
		// Dequeue a vertex from queue ( Refer http://goo.gl/35oz8 ) 
		int u = q.front(); 
		q.pop(); 
		// Return false if there is a self-loop 
		if (G[u][u] == 1) 
		return false; 
		// Find all non-colored adjacent vertices 
		for (int v = 0; v < V; ++v) 
		{ 
			// An edge from u to v exists and 
			// destination v is not colored 
			if (G[u][v] && colorArr[v] == -1) 
			{ 
				// Assign alternate color to this adjacent v of u 
				colorArr[v] = 1 - colorArr[u]; 
				q.push(v); 
			} 
			// An edge from u to v exists and destination 
			// v is colored with same color as u 
			else if (G[u][v] && colorArr[v] == colorArr[u]) 
				return false; 
		} 
	} 
	// If we reach here, then all adjacent 
	// vertices can be colored with alternate color 
	return true; 
} 
//Program to test above function 
int main() 
{ 
	int G[][V] = {{0, 1, 0, 1}, 
		{1, 0, 1, 0}, 
		{0, 1, 0, 1}, 
		{1, 0, 1, 0} 
	}; 
	isBipartite(G, 0) ? cout << "Yes, the graph is Bipartite" : cout << "No, the graph is not Bipartite"; 
	return 0; 
}