HDU 产生冠军 2094

题目链接

思路

#include<cstdio>
#include<queue>
#include<iostream>
#include<vector>
#include<map>
#include<cstring>
#include<string>
#include<set>
#include<stack>
#include<algorithm>
#define cle(a) memset(a,0,sizeof(a))
#define inf(a) memset(a,0x3f,sizeof(a))
#define ll long long
#define Rep(i,a,n) for(int i=a;i<=n;i++)
using namespace std;
#define INF2 9223372036854775807ll
const int INF = ( 2e9 ) + 2;
const ll maxn = 1e3+10;
map<string,int> mp;
int In[maxn];
int main()
{
int n;
while(~scanf("%d",&n)&&n)
{
string a,b;
memset(In,0,sizeof(In));
int cnt=1;
mp.clear();
for(int i=0;i<n;i++)
{
cin>>a>>b;
if(mp[a]==0)mp[a]=cnt++;
if(mp[b]==0)mp[b]=cnt++;
In[mp[b]]++;
}
int f=0;
for(int i=1;i<cnt;i++)
if(In[i]==0)f++;
if(f==1)printf("Yes\n");
else printf("No\n");

}
}