BFS-GRAPH-ALGO.cpp

// BFS algorithm in C++

#include<iostream>
#include<list>

usingnamespacestd;

classGraph {
int numVertices;
 list<int>* adjLists;
bool* visited;

public:
Graph(int vertices);
voidaddEdge(int src, int dest);
voidBFS(int startVertex);
};

// Create a graph with given vertices,
// and maintain an adjacency list
Graph::Graph(int vertices) {
 numVertices = vertices;
 adjLists = new list<int>[vertices];
}

// Add edges to the graph
voidGraph::addEdge(int src, int dest) {
 adjLists[src].push_back(dest);
 adjLists[dest].push_back(src);
}

// BFS algorithm
voidGraph::BFS(int startVertex) {
 visited = newbool[numVertices];
for (int i = 0; i < numVertices; i++)
 visited[i] = false;

 list<int> queue;

 visited[startVertex] = true;
 queue.push_back(startVertex);

 list<int>::iterator i;

while (!queue.empty()) {
int currVertex = queue.front();
 cout << "Visited " << currVertex << "";
 queue.pop_front();

for (i = adjLists[currVertex].begin(); i != adjLists[currVertex].end(); ++i) {
int adjVertex = *i;
if (!visited[adjVertex]) {
 visited[adjVertex] = true;
 queue.push_back(adjVertex);
 }
 }
 }
}

intmain() {
 Graph g(4);
 g.addEdge(0, 1);
 g.addEdge(0, 2);
 g.addEdge(1, 2);
 g.addEdge(2, 0);
 g.addEdge(2, 3);
 g.addEdge(3, 3);

 g.BFS(2);

return0;
}