ROADS Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 13436   Accepted: 4921 Description N cities named with numbers 1 ... N are connected with one-way roads. Each road has two parameters associated with it : the road length and the toll…

/*两个约束条件求最短路,用优先队列*/ #include<stdio.h> #include<string.h> #include<queue> using namespace std; #define N 110 struct node { int u,v,w,f,next; }bian[N*N*4]; int head[N],yong,money; void init() { memset(head,-1,sizeof(head)); yong=0; } stru…

题目链接 题意 : 求从1城市到n城市的最短路.但是每条路有两个属性,一个是路长,一个是花费.要求在花费为K内,找到最短路. 思路 :这个题好像有很多种做法,我用了BFS+优先队列.崔老师真是千年不变的SPFA啊,链接.还有一个神用了好几种方法分析,链接 . 用优先队列控制长度,保证每次加的都是最短的,每次从队列中取元素,沿着取出来的点往下找,如果费用比K少再加入队列,否则不加,这样可以省时间. #include <stdio.h> #include <string.h> #inc…

迪杰斯塔拉裸题 最大花费 n个点 m条有向边 起点终点 路径长度 路径花费 问:在花费限制下,最短路径的长度 #include <iostream> #include <string> #include <cstring> #include <algorithm> #include <cstdio> #include <cctype> #include <queue> #include <stdlib.h> #…

### POJ 1724 题目链接 ### 题目大意: 给你 N 个点 ,M 条有向路,走每条路需要花费 C 元,这段路的长度为 L . 给你 K 元,问你能否从 1 走到 N 点且花费不超过 K 元.如果可以,输出出最短距离,否则输出 -1 . 显然分层图最短路,这里 dist[i][j] 表示从 1 到 i 点 且 所剩钱数为 j 时的最短路,然后跑一遍 dijkstra 即可. PS:在优先队列先到达 N 点的即为答案,可以直接返回,不需要等队列走完再 O(N)找最小值,时间会很快(这里还…

Heavy Transportation POJ 1797 最短路变形 题意 原题链接 题意大体就是说在一个地图上,有n个城市,编号从1 2 3 ... n,m条路,每条路都有相应的承重能力,然后让你求从编号为1的城市到编号为n的城市的路线中,最大能经过多重的车. 解题思路 这个题可以使用最短路的思路,不过转移方程变了\(dis[j]=max(dis[j], min(dis[u], e[u][j]))\).这里dis[j]表示从标号为1的点到达编号为j的点的路径中,最小的承重能力,就像短板效应样…

POJ 1724 ROADS Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 12766   Accepted: 4722 Description N cities named with numbers 1 ... N are connected with one-way roads. Each road has two parameters associated with it : the road length and…

poj 3253 Fence Repair 优先队列 Description Farmer John wants to repair a small length of the fence around the pasture. He measures the fence and finds that he needs N (1 ≤ N ≤ 20,000) planks of wood, each having some integer length Li (1 ≤ Li ≤ 50,000) u…

ROADS Time Limit: 1000MS Memory Limit: 65536K Total Submissions: 12436 Accepted: 4591 Description N cities named with numbers 1 - N are connected with one-way roads. Each road has two parameters associated with it : the road length and the toll that…

题目链接:http://poj.org/problem?id=1724 思路: 有限制的最短路,或者说是二维状态吧,在求最短路的时候记录一下花费即可.一开始用SPFA写的,900MS险过啊,然后改成Dijkstra+priority_queue,60MS,orz. SPFA: #include<iostream> #include<cstdio> #include<cstring> #include<algorithm> #include<queue&…