Graphs

Detect Cycle in Directed Graph using DFS Algo

CycleDetectionDirected.cpp

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+#include<bits/stdc++.h>
+using namespace std;
+
+class Solution
+{
+    public:
+    bool cycleDFS(int node,vector<int> adj[], vector<int> &vis, vector<int> &dfsvis)
+    {
+        vis[node]=1;
+        dfsvis[node]=1;
+
+        for(auto it:adj[node])
+        {
+            if(!vis[it])
+            {
+            if(cycleDFS(it,adj,vis,dfsvis))return true;
+            }
+            else if(dfsvis[it])
+            return true;
+        }
+        dfsvis[node]=0;
+        return false;
+    }
+    public:
+	//Function to detect cycle in a directed graph.
+	bool isCyclic(int V, vector<int> adj[]) 
+	{
+	   vector<int>vis(V,0);
+	   vector<int>dfsvis(V,0);
+	   for(int i=0;i<V;i++)
+	   {
+	       if(!vis[i])
+	       {
+	           if(cycleDFS(i,adj,vis,dfsvis))
+	           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);
+    	}
+
+    	Solution obj;
+    	cout << obj.isCyclic(V, adj) << "\n";
+    }
+
+    return 0;
+}