1003 - Drunk.cpp

//1003 - Drunk
#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define mp make_pair
#define INF 1<<28
#define lli long long int
#define ulli unsigned long long int
#define MX 1000000000
#define SIZE 1000000
#define sfint(a) scanf("%d",&a)
#define sfllint(a) scanf("%lld",&a)
#define sfch(a) scanf("%c",&a)
#define sfchsq(a) scanf("%s",a)
#define sfint2(a,b) scanf("%d%d",&a,&b)
#define sfllint2(a,b) scanf("%lld%lld",&a,&b)
#define sfllint3(a,b,c) scanf("%lld%lld%lld",&a,&b,&c)
#define sfllint4(a,b,c,d) scanf("%lld%lld%lld%lld",&a,&b,&c,&d)
#define sfint3(a,b,c) scanf("%d%d%d",&a,&b,&c)
#define forlp0(i,n) for(int i=0;i<n;i++)
#define forlp1(i,n) for(int i=1;i<=n;i++)
#define forlp2(i,n) for(int i=2;i<=n;i++)
#define forlpa(i,a,n) for(int i=a;i<=n;i++)
#define rvforlp(i,n) for(int i=n-1;i>=0;i--)
#define rvforlp1(i,n) for(int i=n-1;i>0;i--)
#define mem(a,b) memset(a, (b), sizeof(a))
#define mem2d(a,n,m,b) memset(a, (b), sizeof(a[0][0] * n * m))
#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define SZ 100009
typedef pair<int,int> PII;

int main(){
//IOS
	
	int testCase;
	sfint(testCase);
	forlp1(t, testCase){
		map<string,int> drink;
		vector<int> graph[SZ];
		int m;
		int it=0;
		sfint(m);
		forlp0(i, m){
			string a, b;
			cin>>a>>b;
			
			if( drink.find(a) == drink.end() ) drink[a] = ++it;
			if( drink.find(b) == drink.end() ) drink[b] = ++it;
		
			graph[drink[a]].pb(drink[b]);
		}
		bool circle =  false;
		forlp1(i, it){
				int visited[SZ] = {0};
				queue<int> q;
				q.push(i);
				visited[i] = 1;
				while(!q.empty()){
					int u = q.front();
					q.pop();
					forlp0(j, (int)graph[u].size()){
						if(graph[u][j] == i){
							circle = true;
							break;
						}
						if(visited[graph[u][j]] == 0){
							q.push(graph[u][j]);
							visited[graph[u][j]] = 1;
						}
					}
					if(circle)
						break;
				}
			if(circle)
				break;
		}
		
		cout<<"Case "<<t<<": ";
		
		string answer = circle ? "No" : "Yes";
		cout<<answer<<endl;
		
	}
	
	return 0;
}