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DetecCycleGraph.cpp
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DetecCycleGraph.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.
bool findCycle(int V, vector<int> adj[],int sv,bool isVisited[],int itsParent[]) {
queue<int> pendingVertices;
pendingVertices.push(sv);
isVisited[sv] = true;
itsParent[sv] = sv;
while(!pendingVertices.empty()) {
int currentValue = pendingVertices.front();
pendingVertices.pop();
for(int i = 0; i < adj[currentValue].size(); i++) {
if(!isVisited[adj[currentValue][i]]) {
isVisited[adj[currentValue][i]] = true;
pendingVertices.push(adj[currentValue][i]);
itsParent[adj[currentValue][i]] = currentValue;
}
else {
if(itsParent[currentValue] != adj[currentValue][i])
return true;
}
}
}
return false;
}
bool isCycle(int V, vector<int> adj[]) {
// Code here
bool isVisited[V] = {false};
int itsParent[V];
for(int i=0;i<V;i++) {
if(!isVisited[i]) {
if(findCycle(V,adj,i,isVisited,itsParent))
return true;
}
}
return false;
}
};
// { Driver Code Starts.
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;
} // } Driver Code Ends