Detect Cycle in a directed graph

Author: shwetank0714

Graph/detectCycleIn_Directed_graph.cpp

@@ -0,0 +1,69 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+
+
+
+/*  Function to check if the given graph contains cycle
+*   V: number of vertices
+*   adj[]: representation of graph
+*/
+bool check_cycle(vector<int> g[],int *visit,int *cycle,int k){
+    cycle[k] = 1;
+    visit[k] = 1;
+    
+    for(auto i = g[k].begin();i!=g[k].end();i++){
+        if(cycle[*i] == 1){
+            return true;
+        }
+        
+        else if(cycle[*i] == 0)
+            if(visit[*i] != 0 && check_cycle(g,visit,cycle,*i))return true;
+        
+    }
+    cycle[k] = 0;
+    return false;
+}
+
+
+bool isCyclic(int V, vector<int> adj[])
+{
+    int visited[V] = {0};
+    int cycleCheck[V] = {0};
+    for(int i=0;i<V;i++){
+        if(visited[i] == 0){
+            if(check_cycle(adj,visited,cycleCheck,i))
+                return true;
+        }    
+    }
+    return false;
+    
+}
+
+
+
+
+int main() {
+	
+	int t;
+	cin >> t;
+	
+	while(t--){
+	    
+	    int v, e;
+	    cin >> v >> e;
+	    
+	    vector<int> adj[v];
+	    
+	    for(int i =0;i<e;i++){
+	        int u, v;
+	        cin >> u >> v;
+	        adj[u].push_back(v);
+	    }
+	    
+	    cout << isCyclic(v, adj) << endl;
+	    
+	}
+	
+	return 0;
+}