hdu2094 产生冠军

#include<stdio.h>
#include<string.h>
struct node{
    char win[20],lost[20];
    int score;
}game[1000];
int main()
{
    int i,j,n,flag;
    while(scanf("%d",&n),n)
    {
        memset(game,0,sizeof(game));
        for(i=0;i<n;++i){
            scanf("%s%s",game[i].win,game[i].lost);
            game[i].score=1;
        }
        for(i=0;i<n;++i)
            for(j=0;j<n;++j)
                if(!strcmp(game[i].lost,game[j].win))
                    game[j].score=0;
        for(flag=0;flag<n;++flag)
            if(game[flag].score) break;
        if(flag==n){
            puts("No");
            continue;
        }else{
            for(i=flag+1;i<n;++i)
                if(game[i].score&&strcmp(game[i].win,game[flag].win)) break;
            if(i==n) puts("Yes");
            else puts("No");
        }
    }
    return 0;
}