hdu2962Trucking 二分+最短路

//一个无向图，每一条路有限制载重和长度
//问从起点到终点的最大载重，以及在最大载重的情况下的最短路是多少
//二分最大栽重，对于每个载重，小于这个载重的路径不走
#include<iostream>
#include<cstring>
#include<cstdio>
using namespace std ;
const int maxn = 1010 ;
const int inf = 0x3f3f3f3f ;
int vis[maxn] , dis[maxn] ;
struct Edge
{
    int v , w , h ;
    int next ;
}edge[maxn*maxn] ;
int head[maxn] , nedge ,n;
void addedge(int u , int v , int h, int w)
{
    edge[nedge].v = v ;
    edge[nedge].h = h ;
    edge[nedge].w = w ;
    edge[nedge].next = head[u] ;
    head[u] = nedge++ ;
}
bool dijkstra(int st , int en , int h)
{
    memset(vis , 0 , sizeof(vis)) ;
    for(int i = 1;i <= n;i++)
    dis[i] = i == st ? 0 : inf ;
    while(1)
    {
        int mi = inf ;
        int pos ;
        for(int i = 1;i <= n;i++)
        if(!vis[i] && dis[i] < mi)
        mi = dis[pos = i] ;
        if(mi == inf)break ;
        vis[pos] = 1 ;
        for(int i = head[pos] ; i != -1 ;i = edge[i].next)
        {
            if(edge[i].h < h)continue ;
            int v = edge[i].v  ;
            if(dis[v] > dis[pos] + edge[i].w)
           dis[v] = dis[pos] + edge[i].w ;
        }
    }
    if(dis[en] != inf)return true ;
    else return false ;
}
int find(int st , int en , int lim)
{
    int l = 0 ;
    int r = lim ;
    while(l <= r)
    {
        int mid = (l + r) >> 1 ;
        if(dijkstra(st , en , mid))
        l = mid + 1 ;
        else r = mid - 1 ;
    }
    return r ;
}
int main()
{
   // freopen("in.txt" ,"r" , stdin) ;
    int  m , st , en , lim ;
    int cas = 0 ;
    while(scanf("%d%d" ,&n , &m) && (n + m))
    {
        memset(head , -1 , sizeof(head)) ;
        nedge = 0 ;
        while(m--)
        {
            int u , v , h , w ;
            scanf("%d%d%d%d" , &u , &v , &h , &w) ;
            if(h == -1) h = inf ;
            addedge(u , v , h , w) ;
            addedge(v , u , h, w) ;
        }
        scanf("%d%d%d" , &st , &en , &lim) ;
        int ans = find(st , en ,lim) ;
        if(cas) puts("") ;
        printf("Case %d:\n" , ++cas) ;
        if(ans < 0)
        puts("cannot reach destination");
        else
        {
            printf("maximum height = %d\n" , ans) ;
            dijkstra(st , en , ans) ;
            printf("length of shortest route = %d\n" , dis[en]) ;
        }
    }
    return  0 ;
}