POJ2240

floyd

题意：给定一些money以及之间的转化，询问最后能不能让某种money升值

#include<stdio.h>
#include<map>
#include<string>
#include<iostream>
using namespace std;
const int maxn = 105;
map<string,int>mp;
double mat[ maxn ][ maxn ];
double fmax( double a ,double b ){
    return a>b?a:b;
}
int main(){
    int n;
    int cnt=1;
    while( scanf("%d",&n)==1,n ){
        string s;
        for( int i=1;i<=n;i++ ){
            cin>>s;
            mp[ s ]=i;
        }
        int m;
        scanf("%d",&m);
        string s1,s2;
        double tmp;
        for( int i=0;i<maxn;i++ )
            for( int j=0;j<maxn;j++ )
                if( i==j )
                    mat[ i ][ j ]=1.0;
                else
                    mat[ i ][ j ]=0.0;
        for( int i=1;i<=m;i++ ){
            cin>>s1;
            cin>>tmp;
            cin>>s2;
            mat[ mp[ s1 ] ][ mp[ s2 ] ]=tmp;
        }
        for( int k=1;k<=n;k++ ){
            for( int i=1;i<=n;i++ ){
                for( int j=1;j<=n;j++ ){
                    if( mat[i][k]>0 && mat[k][j]>0 ){
                        mat[i][j]=fmax( mat[i][j],mat[i][k]*mat[k][j]);
                    }
                }
            }
        }
        int flag=-1;
        for( int i=1;i<=n;i++ )
            if( mat[i][i]>1 ){
                flag=1;
                break;
            }
        printf("Case %d: ",cnt++);
        if( flag==1 )printf("Yes\n");
        else printf("No\n");
    }
    return 0;
}