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;

}