求次短路,dijkstra时同时记下到某点的最短距离和次短距离即可. #include<cstdio> #include<cstring> #include<algorithm> #include<vector> #include<queue> #include<map> #include<cmath> #include<ctime> #include<set> #define pa pair<…

注意:如果是这么个写法,堆数组要开成n+m的. 为什么呢?设想一下从1到2有m条长度递减的路,这岂不是要入队m次-- #include <algorithm> #include <iostream> #include <cstring> #include <cstdio> using namespace std; struct Edge{ int too, nxt, val; }edge[200005]; struct Node{ int idd, val;…

P2865 [USACO06NOV]路障Roadblocks 最短路(次短路) 直接在dijkstra中维护2个数组:d1(最短路),d2(次短路),然后跑一遍就行了. attention:数据有不同权值的重边(40ptsQAQ) #include<iostream> #include<cstdio> #include<cstring> #include<queue> #include<cctype> using namespace std; t…

Dijkstra 算法是一种用于计算带权有向图中单源最短路径(SSSP:Single-Source Shortest Path)的算法,由计算机科学家 Edsger Dijkstra 于 1956 年构思并于 1959 年发表.其解决的问题是:给定图 G 和源顶点 v,找到从 v 至图中所有顶点的最短路径. Dijkstra 算法采用贪心算法(Greedy Algorithm)范式进行设计.在最短路径问题中,对于带权有向图 G = (V, E),Dijkstra 算法的初始实现版本未使用最小优先…

Dijkstra是解决单源最短路径的一般方法,属于一种贪婪算法. 所谓单源最短路径是指在一个赋权有向图中,从某一点出发,到另一点的最短路径. 以python代码为例,实现Dijkstra算法 1.数据结构设计 假设图以单边列表的方式进行输入,本例使用如下的一个图来进行分析: E = ((1,2,2), (1,4,1), (2,4,3), (2,5,10), (3,1,4), (3,6,5), (4,3,2), (4,6,8), (4,7,4), (4,5,2), (5,7,6), (7,6,1)…

最小费用最大流板子,没有压行.利用重标号让边权非负,用Dijkstra进行增广,在理论和实际上都比SPFA增广快得多.教程略去.转载请随意. #include <cstdio> #include <cstring> #include <algorithm> #include <functional> #include <queue> using namespace std; ; const int inf = 0x33333333; typede…

传送门 Frogger Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 39453   Accepted: 12691 Description Freddy Frog is sitting on a stone in the middle of a lake. Suddenly he notices Fiona Frog who is sitting on another stone. He plans to visit…

传送门 Til the Cows Come Home Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 46727   Accepted: 15899 Description Bessie is out in the field and wants to get back to the barn to get as much sleep as possible before Farmer John wakes her for…

all the nodes should be carectorized into three groups: (visited, front, unknown) we should pay special attention to front group. The Dijkstra Algorithm: front = start node while front is not empty: get node n with minimum cost in the front group, an…

题目链接 中文题,迪杰斯特拉最短路径算法模板题. #include<stdio.h> #include<string.h> #define INF 0x3f3f3f3f ],vis[],map[][],low[],a[]; int n,m,start,end; void dijkstra() { int min,max,i,j,next; memset(visit,,sizeof(visit)); visit[start]=; ;i<n;i++) { vis[i]=map[s…