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Detect_cycle.cpp
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#include<bits/stdc++.h>
using namespace std;
// } Driver Code Ends
class Solution
{
public:
//Function to detect cycle in an undirected graph.
void DFSUtil(vector<int>vec[],int u,vector<int>visited,bool &flag)
{
for(int i=0;i<vec[u].size();i++)
{
if(visited[vec[u][i]]==1)
visited[vec[u][i]]=2;
else if(visited[vec[u][i]]==0)
{visited[vec[u][i]]=1;
return DFSUtil(vec,vec[u][i],visited,flag);
visited[vec[u][i]]=0;
}
else
{
flag=true;
return;
}
}
}
bool isCycle(int V, vector<int>adj[])
{
vector<int>visited(V+1,0);
bool flag=false;
for(int i=0;i<V;i++)
{
visited[i]=1;
DFSUtil(adj,i,visited,flag);
if(flag==true)
return true;
}
return false;
}
};
int main(){
int tc;
cin >> tc;
while(tc--){
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);
adj[v].push_back(u);
}
Solution obj;
bool ans = obj.isCycle(V, adj);
if(ans)
cout << "1\n";
else cout << "0\n";
}
return 0;
}