#include <bits/stdc++.h>
using namespace std;
// Number of vertices in the graph
#define N 13
// data structure to store graph edges
struct Edge {
int src, dest;
};
// class to represent a graph object
class Graph
{
public:
// A array of vectors to represent adjacency list
vector<int> adjList[N];
// Constructor
Graph(vector<Edge> edges)
{
// add edges to the undirected graph
for (unsigned i = 0; i < edges.size(); i++)
{
int src = edges[i].src;
int dest = edges[i].dest;
adjList[src].push_back(dest);
adjList[dest].push_back(src);
}
}
};
// Perform BFS recursively on graph
void recursiveBFS(Graph const &graph, queue<int> &q,
vector<bool> &discovered)
{
if (q.empty())
return;
// pop front node from queue and print it
int v = q.front();
q.pop();
cout << v << " ";
// do for every edge (v -> u)
for (int u : graph.adjList[v])
{
if (!discovered[u])
{
// mark it discovered and push it into queue
discovered[u] = true;
q.push(u);
}
}
recursiveBFS(graph, q, discovered);
}
// main function
int main()
{
// vector of graph edges as per above diagram
vector<Edge> edges = {
{2, 5}, {2, 6}, {5, 9},
{5, 10}, {4, 7}, {4, 8}, {7, 11}, {7, 12}
};
// create a graph from edges
Graph graph(edges);
// stores vertex is discovered or not
vector<bool> discovered(N);
// create a queue used to do BFS
queue<int> q;
// mark source vertex as discovered
discovered[1] = true;
// push source vertex into the queue
q.push(1);
// start BFS traversal from vertex i
recursiveBFS(graph, q, discovered);
return 0;
}
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