hdu 1217 Arbitrage

Flody多源最短路

#include<cstdio>
#include<cstring>
#include<string>
#include<cmath>
#include<map>
#include<algorithm>
#include<iostream>
using namespace std;

const int maxn=35;
map<string,int>zh;
string s,s1,s2;
double jz[maxn][maxn],A[maxn][maxn];
int u,v,n,m;

void floyd()
{
    int i,j,k;
    for(i=0;i<=n;i++) for(j=0;j<=n;j++) A[i][j]=jz[i][j];
    for(k=1;k<=n;k++)
    {
        for(i=1;i<=n;i++)
        {
            for(j=1;j<=n;j++)
            {
                if(k==i||k==j) continue;
                if(A[i][k]*A[k][j]>A[i][j]) A[i][j]=A[i][k]*A[k][j];            
            }
        }
    }
}

int main()
{
    int i,j,_=1; double cost;
    while(~scanf("%d",&n))
    {
        if(!n) break; zh.clear();
        for(i=1;i<=n;i++) {cin>>s;zh[s]=i;}
        scanf("%d",&m);
        memset(jz,0,sizeof(jz));
        for(i=0;i<m;i++)
        {
            cin>>s1; scanf("%lf",&cost); cin>>s2;
            u=zh[s1];v=zh[s2];  
            jz[u][v]=cost;
        }
        int flag=0;    
        floyd();
        for(i=1;i<=n;i++)
        {
            for(j=1;j<=n;j++)
            {
                if(A[i][j]*A[j][i]>1.0) {flag=1;break;}
            }
            if(flag) break;
        }
        printf("Case %d: ",_++);
        if(flag) printf("Yes\n");
        else printf("No\n");        
    }
    return 0;
}