Breadth-First Search (BFS):

• Explores neighbors level by level (breadth-wise).
• Uses a queue.
• Time complexity: \(O(V + E)\)
• Applications: Shortest path in an unweighted graph.

void BFS(int start, vector<vector<int>> &adj) {
    queue<int> q;
    vector<bool> visited(adj.size(), false);
    q.push(start);
    visited[start] = true;

    while (!q.empty()) {
        int node = q.front();
        q.pop();

        // Process node
        cout << node << " ";

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

Depth-First Search (DFS):

• Explores as deep as possible along one branch before backtracking (depth-wise).
• Uses a stack (or recursion).
• Time complexity: \(O(V + E)\)
• Applications: Cycle detection, pathfinding.

void DFS(int node, vector<vector<int>> &adj, vector<bool> &visited) {
    visited[node] = true;
    cout << node << " "; // Process node

    for (int neighbor : adj[node]) {
        if (!visited[neighbor]) {
            DFS(neighbor, adj, visited);
        }
    }
}