From 39ce2893304c7a501973937dc32911a993878047 Mon Sep 17 00:00:00 2001
From: 17ucs091 <17ucs091@github.com>
Date: Tue, 20 Oct 2020 14:42:00 +0530
Subject: [PATCH] Added Detect cycles in Undirected Graph

---
 graph_problems/DetectCycleUndirectedGraph.c++ | 55 +++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 graph_problems/DetectCycleUndirectedGraph.c++

diff --git a/graph_problems/DetectCycleUndirectedGraph.c++ b/graph_problems/DetectCycleUndirectedGraph.c++
new file mode 100644
index 0000000..9a70a0b
--- /dev/null
+++ b/graph_problems/DetectCycleUndirectedGraph.c++
@@ -0,0 +1,55 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+bool dfs(vector<int> g[], int start,vector<int> &visited) {
+    visited[start]=1;
+    int flag=0,len=0;
+    for(int x:g[start]){
+        if(!visited[x]){
+            flag=1;
+            if(dfs(g,x,visited))
+                return true;
+        }
+        else{
+            len++;
+        }
+        
+        if(len>1)
+            return true;
+    }
+    
+    return false;
+}
+
+bool isCyclic(vector<int> g[], int n)
+{
+  
+    vector<int> visited(n);
+    int i;
+    for(i=0;i<n;i++){
+        if(!visited[i]){
+            if(dfs(g,i,visited))
+                return true;
+        }
+        
+    }
+return false;
+}
+
+
+int main(){
+
+ 
+    int v,e;
+    cin>>v>>e;
+    vector<int> adj[v];
+    int x,y;
+    for(int i=0;i<e;i++){
+        cin>>x>>y;
+        adj[x].push_back(y);
+        adj[y].push_back(x);
+
+    }
+    cout<<isCyclic(adj,v)<<"\n";
+
+}
\ No newline at end of file