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Create Cycle Detection in Directed Graph using BFS(Kahn's Algorithm).cpp

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	`1`	`+#include<bits/stdc++.h>`
	`2`	`+using namespace std;`
	`3`	`+`
	`4`	`+class Solution {`
	`5`	`+public:`
	`6`	`+ bool isCyclic(int N, vector<int> adj[]) {`
	`7`	`+ queue<int> q;`
	`8`	`+ vector<int> indegree(N, 0);`
	`9`	`+ for(int i = 0;i<N;i++) {`
	`10`	`+ for(auto it: adj[i]) {`
	`11`	`+ indegree[it]++;`
	`12`	`+ }`
	`13`	`+ }`
	`14`	`+`
	`15`	`+ for(int i = 0;i<N;i++) {`
	`16`	`+ if(indegree[i] == 0) {`
	`17`	`+ q.push(i);`
	`18`	`+ }`
	`19`	`+ }`
	`20`	`+ int cnt = 0;`
	`21`	`+ while(!q.empty()) {`
	`22`	`+ int node = q.front();`
	`23`	`+ q.pop();`
	`24`	`+ cnt++;`
	`25`	`+ for(auto it : adj[node]) {`
	`26`	`+ indegree[it]--;`
	`27`	`+ if(indegree[it] == 0) {`
	`28`	`+ q.push(it);`
	`29`	`+ }`
	`30`	`+ }`
	`31`	`+ }`
	`32`	`+ if(cnt == N) return false;`
	`33`	`+ return true;`
	`34`	`+ }`
	`35`	`+};`
	`36`	`+`
	`37`	`+`
	`38`	`+`
	`39`	`+int main()`
	`40`	`+{`
	`41`	`+`
	`42`	`+ int t;`
	`43`	`+ cin >> t;`
	`44`	`+ while(t--)`
	`45`	`+ {`
	`46`	`+ int V, E;`
	`47`	`+ cin >> V >> E;`
	`48`	`+`
	`49`	`+ vector<int> adj[V];`
	`50`	`+`
	`51`	`+ for(int i = 0; i < E; i++)`
	`52`	`+ {`
	`53`	`+ int u, v;`
	`54`	`+ cin >> u >> v;`
	`55`	`+ adj[u].push_back(v);`
	`56`	`+ }`
	`57`	`+`
	`58`	`+ Solution obj;`
	`59`	`+ cout << obj.isCyclic(V, adj) << "\n";`
	`60`	`+ }`
	`61`	`+`
	`62`	`+ return 0;`
	`63`	`+}`

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