Test case issue [Forwarding Emails (LOJ-1417)]

[Tanzimbn]

https://lightoj.com/problem/forwarding-emails

Test case is missing which could give TLE for the tutorial solution.

#include<bits/stdc++.h>
using namespace std;
int vis[50005],dist[50005],adjacent[50005],cnt=0;
int dfs(int uu)
{
    vis[uu]=1;
    int vv=adjacent[uu];
    if(!vis[vv])
    {
        cnt++;
        dfs(vv);
    }
    vis[uu]=0;
    return dist[uu]=cnt;

}
main()
{   
    int ts,cs=1;
    scanf("%d",&ts);
    while(ts--)
    {
        int n,u,v,mx=0,ans=0;
        scanf("%d",&n);
        for(int i=1;i<=n;i++)
        {
            scanf("%d%d",&u,&v);
            adjacent[u]=v;
        }
        memset(vis,0,sizeof(vis));
        memset(dist,-1,sizeof(dist));
        for(int i=1;i<=n; i++)
        {
            cnt=1;
            if(dist[i]==-1)
            {
                dfs(i);
                dist[i]=cnt;
            }
            if(cnt>mx)
            {
                mx=cnt;
                ans=i;
            }
        }

        printf("Case %d: %d\n",cs++,ans);
    }
}

Test case :

1
50000
1 2
2 1
3 2
4 3
5 4
6 5
7 6
8 7
9 8
10 9
11 10
...
...
49998 49997
49999 49998
50000 49999

I also can make number of test cases 20 and repeat the same graph 20 times.