poj 1724（最短路）

#include<iostream>
#include<cstdio>
#include<queue>
#include<vector>
using namespace std;
#define MAXN 105
int n,k;
struct B
{
   int end,len,toll;
       friend bool operator<(B x,B y)
    {
        if(x.len!=y.len)
            return x.len>y.len;
        return x.toll>y.toll;
    }
};
vector<B> v[MAXN];
priority_queue<B> pq;
int bfs()
{
    int i;
    B next,now;
    while(!pq.empty()) pq.pop();
    now.end=1;
    now.len=0;
    now.toll=0;
    pq.push(now);
    while(!pq.empty())
    {
        now=pq.top();
        pq.pop();
        if(now.end==n) return now.len;
        for(i=0;i<v[now.end].size();i++)
        {
            if(v[now.end][i].toll+now.toll<=k)
            {
                next=v[now.end][i];
                next.len+=now.len;
                next.toll+=now.toll;
                pq.push(next);
            }
        }
    }
    return -1;
    
}
int main()
{
    int i,x,star,end,len,toll;
    while(scanf("%d%d%d",&k,&n,&x)!=EOF)
    {
        B t;
        for(i=0;i<=n;i++) v[i].clear();
        for(i=1;i<=x;i++)
        {
            scanf("%d%d%d%d",&star,&end,&len,&toll);
            t.end=end;
            t.len=len;
            t.toll=toll;
            v[star].push_back(t);
        }
        printf("%d\n",bfs());
    }
}