class Solution {
  public:

    // Function to detect cycle in an undirected graph.

    bool dfs(int node, int parent, vector<int> adj[], vector<bool> & visited) {
        visited[node] = true;
        for(int neigh : adj[node]) {
            if(!visited[neigh] ) {
                 if(dfs(neigh, node, adj, visited)) {
                     return true;
                 }
            }
            else if(neigh != parent) {
                return true;
            }
        }
        return false;
    }
    bool isCycle(int V, vector<int> adj[]) {
        bool res = false;
        vector<bool> visited(V + 2, false);
        for(int i = 0; i < V; i++) {
            if(!visited[i]) {
                if(dfs(i, -1, adj, visited)) {
                    return true;
                }
                }

        }
        return false;
    }
};