dijkstra

Having trouble Implementing a Custom Comparator for a TreeSet (Dijkstra's)

由 柔情痞子 提交于 2019-12-08 03:04:01
问题 I'm currently trying and implementing my own custom O(N.lgN) solution of Dijkstra's using Adjacency Lists. Now if you are familiar with this algorithm (most likely you are), I was having trouble storing the tuple for each Vertex. If you have no clue what i'm talking about, have alook at: http://qr.ae/LoESY Tuples can easily be stored in C++ using pair <int,int>. Anyways, i found a solution to that and came to know, against all odds, that a similar class DOES exist its called the 'AbstractMap

Variations of Dijkstra's Algorithm for graphs with two weight properties

由 大兔子大兔子 提交于 2019-12-08 02:50:08
问题 I'm trying to find a heuristic for a problem that is mapped to a directed graph with say non-negative weight edges. However, each edge is associated with two weight properties as opposed to only one weight (e.g. say one is distance, and another one showing how good the road's 4G LTE coverage is!). Is there any specific variation of dijkstra , Bellman Ford , or any other algorithm that pursues this objective? Of course, a naive workaround is manually deriving a single weight property as a

Priority queue in Dijkstra's algorithm

由 ε祈祈猫儿з 提交于 2019-12-07 15:00:26
问题 This is my code for Dijkstra's algorithm: #include<iostream> #include<cstdio> #include<vector> #include<queue> #define pp pair<int,int> using namespace std; struct pri { int operator() (const pair<int,int>&p1,const pair<int,int>&p2) { return p1.second<p2.second; } }p; int main() { priority_queue<pp,vector<pp>,pri> q; int n; cin>>n; vector<pp> g[n+1]; int e,u,v,w,i; cin>>e; for(i=0;i<e;i++) { cin>>u>>v>>w; g[u].push_back(pp(v,w)); g[v].push_back(pp(u,w)); } int s; cin>>s; int d[n+1]; for(i=1;i

Modified Dijkstra to find most optimized shortest path given extra properties

由 微笑、不失礼 提交于 2019-12-07 12:44:34
问题 This is a follow-up question for a question I asked at here. The problem is mapped to a graph with say non-negative weights on edges (no preference if it can be directed or not). However, along with a weight which is actually distance, we also have another property which is data coverage of the edge which can be important factor which route to select given how severe I need internet on my phone (for real-time gaming for example I need good bandwidth). So overall, we want to somehow find a

how to Update a key in Priority Queue in O(log n ) time in dijkstra's algorithm?

由 耗尽温柔 提交于 2019-12-07 05:00:30
问题 I have been working on dijkstra's algorithm for the past one week one I have the correct running code for it in java. It is using array for the computation of standard findMin function which gives you the vertex with smallest distance.Obviously it is O(n) and Now I am looking to implement it using Priority Queue(Min Heaps) What My thought process is: while (there are unseen Vertex) { vertex= get TheVertex WithSmallest Distance Yet;//(In can be done in O(log n) using heap) for this vertex {

Dijkstras Algorithm doesn't appear to work, my understanding must be flawed

由 ￣綄美尐妖づ 提交于 2019-12-07 04:49:38
问题 Here's my interpretation of how Dijkstra's algorithm as described by wikipedia would deal with the below graph. First it marks the shortest distance to all neighbouring nodes, so A gets 1 and C gets 7. Then it picks the neighbour with the current shortest path. This is A. The origin is marked as visited and will not be considered again. The shortest (and only) path from the origin to B through A is now 12. A is marked as visited. The shortest path from the origin to the Destination through B

Having trouble Implementing a Custom Comparator for a TreeSet (Dijkstra's)

由 一曲冷凌霜 提交于 2019-12-06 13:40:29
I'm currently trying and implementing my own custom O(N.lgN) solution of Dijkstra's using Adjacency Lists. Now if you are familiar with this algorithm (most likely you are), I was having trouble storing the tuple for each Vertex. If you have no clue what i'm talking about, have alook at: http://qr.ae/LoESY Tuples can easily be stored in C++ using pair <int,int>. Anyways, i found a solution to that and came to know, against all odds, that a similar class DOES exist its called the 'AbstractMap.SimpleEntry' Class. Details are given here: https://stackoverflow.com/a/11253710/4258892 Now that you

Variations of Dijkstra's Algorithm for graphs with two weight properties

由 蹲街弑〆低调 提交于 2019-12-06 11:17:04
I'm trying to find a heuristic for a problem that is mapped to a directed graph with say non-negative weight edges. However, each edge is associated with two weight properties as opposed to only one weight (e.g. say one is distance, and another one showing how good the road's 4G LTE coverage is!). Is there any specific variation of dijkstra , Bellman Ford , or any other algorithm that pursues this objective? Of course, a naive workaround is manually deriving a single weight property as a combination of all of them, but this does not look good. Can it be generalized to cases with multiple

Dijkstra's Algorithm Does not generate Shortest Path?

由 橙三吉。 提交于 2019-12-06 10:29:41
问题 I am working through a shortest path problem using Dijkstra's Algorithm. I am having trouble because the algorithm is supposed to provide the shortest path, but after running the algorithm I get a shorted path by hand. Is this just a by-product of this algorithm? The path I am trying to generate is from a -> z Here is the path that I get from applying the algorithm, taking the shortest distance jump at each vertex I visit: 2 4 2 2 1 2 1 1 8 = 23 a -> d -> g -> k -> r -> n -> q -> p -> t -> z
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