POJ1724 ROADS 费用最短路

//State: POJ1724    Accepted    1188K    32MS    C++    1968B
/*
*题目大意：
*        给定总费用，还有n个城市，m条边，构成的图为单向图，然后
*        m条边有费用，还有距离，求从1->n的最小距离，要求走边时
*        费用要小于边的费用。
*解题思路：
*        用二维dij即可。
*/

#include <queue>
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
using namespace std;

const int MAXN = 105;
const int MAXE = 10005;
const int MAX_COST = 10005;
const int inf = 0x3f3f3f3f;

typedef struct _node
{
    int v, next;
    int l, c;
}N;
N edge[MAXE];
int cntEdge, head[MAXN];

typedef struct _no
{
    int v;
    int c, dis;
    _no(): dis(inf) {}
    _no(int a, int b, int c1): v(a), dis(b), c(c1) {} 
    friend bool operator < (const struct _no &n1, const struct _no &n2)
    {
        return n1.dis > n2.dis;
    }
}priN;

void init()
{
    cntEdge = 0;
    for(int i = 0; i < MAXN; i++)
        head[i] = -1;
}

void addEdge(int u, int v, int l, int c)
{
    edge[cntEdge].v = v;
    edge[cntEdge].l = l;
    edge[cntEdge].c = c;
    edge[cntEdge].next = head[u];
    head[u] = cntEdge++;
}

int dis[MAXN];
int dijkstra(int s, int n, int tol)//1是起点，n是终点
{
    int vst[MAXN] = {0};
    for(int i = 0; i <= n; i++)
        dis[i] = inf;

    priority_queue<priN> Q;
    
    Q.push(priN(s, 0, 0));
    //dis[s] = 0;

    while(!Q.empty())
    {
        priN pre = Q.top();
        Q.pop();
        if(pre.v == n)
            return pre.dis;

        for(int f = head[pre.v]; f != -1; f = edge[f].next)
        {
            int son = edge[f].v;
            int l = edge[f].l;
            int c = edge[f].c;

            if(pre.c + c <= tol)
            {
                //dis[son] = dis[pre.v] + l;
                Q.push(priN(son, pre.dis + l, pre.c + c));
            }
        }
    }
    return -1;
}

int main(void)
{
#ifndef ONLINE_JUDGE
    freopen("in.txt", "r", stdin);
#endif

    int n, tol;
    while(scanf("%d", &tol) == 1)
    {
        int m;
        scanf("%d %d", &n, &m);
        init();
        int u, v, l, c;
        for(int i = 0; i < m; i++)
        {
            scanf("%d %d %d %d", &u, &v, &l, &c);
            addEdge(u, v, l, c);
        }
        int sol = dijkstra(1, n, tol);
        printf("%d\n", sol);
    }
    return 0;
}