POJ 2240 Arbitrage Bellman_ford 判读是否存在正环

#include<stdio.h>
#include<string.h>
#include<cstring>
#include<string>
#include<math.h>
#include<queue>
#include<algorithm>
#include<iostream>
#include<stdlib.h>
#include<cmath>

#define INF 0x3f3f3f3f
#define MAX 1005

using namespace std;

struct node
{
    int u,v;
    double k;
}Map[MAX];

char str[50][100000];
int n,tot,m;
double dist[MAX];

int bellman_ford()
{
    int i,j;

    memset(dist,0,sizeof(dist));

    dist[1]=1;

    for(i=1;i<n;i++)
    {
        for(j=1;j<tot;j++)
        {
            if(dist[Map[j].v] < dist[Map[j].u] * Map[j].k)
                dist[Map[j].v] = dist[Map[j].u] * Map[j].k;
        }
    }

    for(j=1;j<tot;j++)
        if(dist[Map[j].v] < dist[Map[j].u] * Map[j].k)
        return 1;

    return 0;
}

int main()
{
    int i,j,a,b,cas=1,ok;
    char str1[MAX],str2[MAX];
    double num;

    while(scanf("%d",&n),n)
    {
        tot=1;
        for(i=1;i<=n;i++)
        {
            scanf("%s",str[i]);
        }

        scanf("%d",&m);

        for(i=1;i<=m;i++)
        {
            scanf("%s%lf%s",str1,&num,str2);

            for(j=1;j<=n;j++)
            {
                if(strcmp(str[j],str1)==0)
                    a=j;

                if(strcmp(str[j],str2)==0)
                    b=j;
            }

            Map[tot].u=a;
            Map[tot].v=b;
            Map[tot++].k=num;
        }

        ok=bellman_ford();

        if(ok)
            printf("Case %d: Yes\n",cas++);
        else
            printf("Case %d: No\n",cas++);
    }
    return 0;
}