poj 最优比率环

只能说我被一个小错搞得好心痛，本一写好代码感觉写的还优美，但一个小的不能再小的 i 写出u ,害的我正正调了一天。还不的不与别人对比看。OMG！！

具体的分析找别人的吧，说的比我好，要吃个苹果放松下

#include <cstdio>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <queue>
#define maxn 1005
using namespace std;

const int INF = 0x3f3f3f;

double mid;
struct Edge{
	int from,to;
	int fun,cost;
	double dis;
	int next;
	void assign(int a,int b,int c,int d,int e){
		from = a; to = b; cost = c; fun = d;  next = e; //printf("%d %d %d %d \n",from,to,cost,fun);
	}
	void update(double k){
		dis = -(fun - k * cost);
	}
	/*
	void print(){
		printf("%d %d %d %d %.2lf\n",from,to,cost,fun,dis);
	}*/	
}edge[5*maxn]; 
int F[maxn];
int n,m;
int head[maxn];
int pv = 1;


void Addedge(int a,int b,int c,int d){
	int e = head[a];
	head[a] = pv;
	edge[pv++].assign(a,b,c,d,e);
}
bool SPFA(){
	int cnt[maxn];
	bool inq[maxn];
	double d[maxn];
	memset(cnt,0,sizeof(cnt));
	memset(inq,0,sizeof(inq));
	for(int i=1;i<=n;i++) d[i] = INF;                                             
	queue<int> Q;
	while(!Q.empty()) Q.pop();
    Q.push(1);
	inq[1] = true; 
	d[1] = 0;
	while(!Q.empty()){
	    int u = Q.front(); Q.pop(); inq[u] = false; 
		for(int i=head[u];i != -1;i=edge[i].next){
			int v = edge[i].to;             
			if(d[v] > d[u] + edge[i].dis){
				d[v] = d[u] + edge[i].dis;  
				if(!inq[v]){
					Q.push(v); inq[v] = true;
					if(++cnt[v] >= n)  return true;
				}
			}
			
		}
	}
	return false;
}
int main()
{
	//if(freopen("input.txt","r",stdin)== NULL)  {printf("Error\n"); exit(0);}
	//if(freopen("output1.txt","w",stdout)== NULL)  {printf("Error\n"); exit(0);}
	cin>>n>>m;
	for(int i=1;i<=n;i++) cin>>F[i];
	memset(head,-1,sizeof(head));
	for(int i=1;i<=m;i++){
		int a,b,c,d;
		cin>>a>>b>>c;
		d = F[b];  
		Addedge(a,b,c,d);
	}
	 
	double R=10000.0,L=0.0,ans = -1;
	while((R-L) > 1e-5){
		mid = (R + L)/2;  
		for(int i=1;i<=m;i++){
			edge[i].update(mid); //edge[i].print();
		}
		if(SPFA())  { ans = mid; L = mid;  }
		else         R = mid;
	}
	if(ans <= 0 ) printf("0\n");
 	else          printf("%.2lf\n",L);
}