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Cycle_in_Directed_Graph.cpp
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Cycle_in_Directed_Graph.cpp
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#include<bits/stdc++.h>
using namespace std;
int visited[10005],visited1[10005];
vector<int> directed[10005];
int dfs2(int node)
{
//cout<<node<<endl;
visited[node]=1;//universal stack
visited1[node]=1;// this visited array is for the dfs( to mark ,the recursion stack in one dfs)
for(int i=0;i<directed[node].size();i++)
{
if(visited1[directed[node][i]]==0 && dfs2(directed[node][i]))
{
return 1;
}
else if(visited[directed[node][i]]==1)
return 1;
}
visited[node]=0;
return 0;
}
int main()
{
//ios_base::sync_with_stdio(false);
//cin.tie(false);
int t;
cin>>t;
while(t--)
{
int n,m;
cin>>n>>m;
for(int i=0;i<=n;i++)
{
directed[i].clear();
}
for(int i=0;i<m;i++)
{
int u,v;
cin>>u>>v;
directed[u].push_back(v);
}
fill(visited,visited+10005,0);
fill(visited1,visited1+10005,0);
bool ans=0;
for(int i=1;i<=n;i++)
{
if(visited1[i]==0)
{
ans=dfs2(i);
//cout<<"i "<<ans<<endl;
}
if(ans==1)
break;
}
if(ans==1)
{
cout<<"Cycle Present in Graph\n";
}
else
{
cout<<"Cycle Not present\n";
}
}
}