poj2240 Arbitrage

跟poj1860类似 判断是否存在正环，bellman-ford每个点做一次正环判断，刚开始以为每种货币都要能升值，错了，后来又因为case后面少打了个空格 晕

code

#include <set>
#include <map>
#include <ctime>
#include <queue>
#include <cmath>
#include <stack>
#include <limits>
#include <vector>
#include <bitset>
#include <string>
#include <cstdio>
#include <cstring>
#include <fstream>
#include <string.h>
#include <iostream>
#include <algorithm>
#define Si set<int>
#define LL long long
#define pb push_back
#define PS printf(" ")
#define Vi vector<int>
#define LN printf("\n")
#define lson l,m,rt << 1
#define rson m+1,r,rt<<1|1
#define SD(a) scanf("%d",&a)
#define PD(a) printf("%d",a)
#define SET(a,b) memset(a,b,sizeof(a))
#define FF(i,a) for(int i(0);i<(a);i++)
#define FD(i,a) for(int i(a);i>=(1);i--)
#define FOR(i,a,b) for(int i(a);i<=(b);i++)
#define FOD(i,a,b) for(int i(a);i>=(b);i--)
#define readf freopen("input.txt","r",stdin)
#define writef freopen("output.txt","w",stdout)
const int maxn = 201;
const long long BigP=999983;
const int INF = 0x3fffffff;
const int dx[]={0,1,0,-1};
const int dy[]={1,0,-1,0};
const double pi = acos(-1.0);
const double eps= 1e-7;
using namespace std;
int N,M,e_cnt;
char name[31][50];
double dis[maxn];
struct edge{
    int from,to;
    double w;
}E[501];
void add_E(int from,int to,double w){
    E[++e_cnt].to=to;
    E[e_cnt].w=w;
    E[e_cnt].from=from;
}
bool bellman_ford(int s){
    SET(dis,0);
    dis[s]=1;
    bool flag;
    while(dis[s]<=1+eps){
        flag=false;
        FOR(i,0,e_cnt){
            if(dis[E[i].to]<dis[E[i].from]*E[i].w){
                dis[E[i].to]=dis[E[i].from]*E[i].w;
                flag=true;
            }
        }
        if(!flag){
            if(dis[s]>1+eps) return true;
            else return false;
        }
    }
    return true;
}
int main(){
    int cnt=1;
    while(~SD(N) &&N){
        e_cnt=0;
        FOR(i,1,N){
            scanf("%s",name[i]);
        }
        char ch[50];int k1,k2;double t;
        SD(M);
        FOR(i,1,M){
            scanf("%s",ch);
            FOR(j,1,N){
                if(!strcmp(ch,name[j])){
                    k1=j;
                }
            }
            scanf("%lf",&t);
            scanf("%s",ch);
            FOR(j,1,N){
                if(!strcmp(ch,name[j])){
                    k2=j;
                }
            }
            add_E(k1,k2,t);
        }
        printf("Case %d: ",cnt++);
        bool flag=false;
        FOR(i,1,N){
            if(bellman_ford(i)){
                flag=true;
                break;
            }
        }
        if(flag) puts("Yes");
        else puts("No");
    }
    return 0;
}