dijkstra

On the Wikipedia page for Dijkstra's algorithm, they mark visited nodes so they wouldn't be added to the queue again. However, if a node is visited then there can be no distance to that node that is shorter, so doesn't the check alt < dist[v] already account for visited nodes? Am I misunderstanding something about the visited set? for each neighbor v of u: alt := dist[u] + dist_between(u, v); // accumulate shortest dist from source if alt < dist[v] && !visited[v]: dist[v] := alt; // keep the shortest dist from src to v previous[v] := u; insert v into Q; // Add unvisited v into the Q to be

I am looking for an explanation why the AStar / A* algorithm is called AStar. All similar (shortest path problem) algorithms are often named like its developer(s), so what is AStar standing for? There were algorithms called A1 and A2. Later, it was proved that A2 was optimal and in fact also the best algorithm possible, so he gave it the name A* which symbolically includes all possible version numbers. Source: In 1964 Nils Nilsson invented a heuristic based approach to increase the speed of Dijkstra's algorithm. This algorithm was called A1. In 1967 Bertram Raphael made dramatic improvements

输入： 6 9 1 1 2 1 1 3 12 2 3 9 2 4 3 3 5 5 4 3 4 4 5 13 4 6 15 5 6 4 输出： 0 1 8 4 13 17 Code: 1 #include<iostream> 2 #include<cstring> 3 #include<queue> 4 using namespace std; 5 #define PII pair<int,int> 6 const int maxn=10000,maxm=1000; 7 int cnt=0,edge[maxm],ver[maxm],nxt[maxm],head[maxn]; 8 int d[maxn]; 9 bool v[maxn];//v[i]表示i点是否松弛 10 priority_queue < PII,vector<PII>,greater<PII> > q;//优先队列，以p.first最小优先 11 inline void add(int x,int y,int z) 12 { 13 cnt++; 14 ver[cnt]=y; 15 edge[cnt]=z; 16 nxt[cnt]=head[x]; 17 head[x]=cnt; 18 } 19 inline void dijk(int t) 20 { 21 int i; 22 memset(d,0x3f,sizeof

给定一个n个点m条边的有向图，图中可能存在重边和自环，所有边权均为正值。 请你求出1号点到n号点的最短距离，如果无法从1号点走到n号点，则输出-1。 输入格式 第一行包含整数n和m。 接下来m行每行包含三个整数x，y，z，表示存在一条从点x到点y的有向边，边长为z 输出格式 输出一个整数，表示1号点到n号点的最短距离。 如果路径不存在，则输出-1。 数据范围 \(1≤n≤500,\) \(1≤m≤105,\) 图中涉及边长均不超过10000 输入样例 3 3 1 2 2 2 3 1 1 3 4 输出样例 3 原题链接： https://www.acwing.com/problem/content/851/ 用 dijkstra算法 解决最短路问题的模板题。 dijkstra算法 的一般流程是： 初始化 dist[1] = 0 ，其余结点的 dist 值为无穷大 找出一个未被标记的、 dist[x] 最小的结点 x ，然后标记 x 扫描结点x的所有出边 (x, y, z) ，若 dist[y] > dist[x] + z ， 那么使用 dist[x]+z 来更新 dist[y] 重复上述2、3步骤，直到所有结点被标记 代码如下： #include <iostream> #include <memory.h> using namespace std; const int N = 502

I am using QuickGraph version 3.6 and I found function SetRootVertex, but no SetTagretVertex. I need this because I am searching short paths in huge graph and this would speed up program a lot. Clases in question are DijkstraShortestPathAlgorithm and AStarShortestPathAlgorithm. I don't think there is a way to this without using events. You could wrap the necessary code in one extension method, making things clear, e.g.: public static class Extensions { class AStarWrapper<TVertex, TEdge> where TEdge : IEdge<TVertex> { private TVertex target; private AStarShortestPathAlgorithm<TVertex, TEdge>

I've been tasked (coursework @ university) to implement a form of path-finding. Now, in-spec, I could just implement a brute force, since there's a limit on the number of nodes to search (begin, two in the middle, end), but I want to re-use this code and came to implement Dijkstra's algorithm . I've seen the pseudo on Wikipedia and a friend wrote some for me as well, but it flat out doesn't make sense. The algorithm seems pretty simple and it's not a problem for me to understand it, but I just can't for the life of me visualize the code that would realize such a thing. Any suggestions/tips?

The question: Find shortest path between two articles in english Wikipedia. Path between article A and B exist if there are articles C(i) and there is a link in article A that leads to article C(1), in article C(1) link that leads to article C(2), ..., in article C(n) is link that leads to article B I'm using Python. URL to download wikipedia article: http://en.wikipedia.org/wiki/Nazwa_artykułu http://en.wikipedia.org/w/index.php?title?Nazwa_artykułu&printable=yes Wikipedia API I have edited my source code, but it still does not work when I include those articles in codes can any one tell me