BFS.cpp

#include <iostream>
#include <vector>
#include <queue>
using namespace std;

void BFS(int start, vector<int> adj[], int vertices)
{
    vector<bool> visited(vertices, false);
    queue<int> q;

    visited[start] = true;
    q.push(start);

    cout << "BFS Traversal starting from vertex " << start + 1 << ": ";

    while (!q.empty())
    {
        int node = q.front();
        q.pop();
        cout << node + 1 << " ";

        for (int neighbor : adj[node])
        {
            if (!visited[neighbor])
            {
                visited[neighbor] = true;
                q.push(neighbor);
            }
        }
    }
    cout << "\n";
}

int main()
{
    int vertices, edges;

    cout << "Enter the number of vertices: ";
    cin >> vertices;
    cout << "Enter the number of edges: ";
    cin >> edges;

    vector<int> adj[100];

    cout << "Enter the edges (u v) where 1 <= u,v <= " << vertices << ":\n";
    for (int i = 0; i < edges; i++)
    {
        int u, v;
        cin >> u >> v;

        adj[u - 1].push_back(v - 1);
        adj[v - 1].push_back(u - 1);
    }

    int startVertex;
    cout << "Enter the starting vertex for BFS: ";
    cin >> startVertex;

    BFS(startVertex - 1, adj, vertices);

    return 0;
}