CODE EXAMPLE FOR CPP

Detect cycle in an undirected graph

//function snippet using DFS
bool dfs(int node,int parent, vector<int> adj[], vector<bool> &check)
    {
        check[node] = true;
        for(auto n1 :adj[node])
        {
            if(!check[n1])
                if(dfs(n1, node, adj, check)) return true;
            else if(n1 != parent) return true;
        }
        return false;
    }
    
    bool isCycle(int V, vector<int> adj[]) {
        vector<bool>check(V, 0);
        //for all the commponents 
        for(int i =0; i < V; i++)
        {
            if(!check[i])
                if (dfs(i, -1, adj, check)) return true;// if a component has a cycle then graph has a cycle 
        }
        return false;
    }