zoj 1967 Fiber Network

#include<iostream>#include<cstdio>#include<cstring>#define maxn 205using namespace std;int map[maxn][maxn];int n,a,b;int main(){    char ch[30];    while(scanf("%d",&n),n){        memset(map,0,sizeof(map));        while(scanf("%d%d",&a,&b),a+b){ scanf("%s",ch); for(int i=0;ch[i]!='';i++)     map[a][b]|=1<<(ch[i]-'a');        }        for(int k=1;k<=n;++k) for(int i=1;i<=n;++i)     for(int j=1;j<=n;++j){         map[i][j]|=(map[i][k]&map[k][j]);        }        while(scanf("%d%d",&a,&b),a+b){ for(int i=0;i<26;++i){     if(map[a][b]&(1<<i))         printf("%c",i+'a'); } if(!map[a][b]) printf("-"); printf("n");        } printf("n");    }    return 0;}