A graph is an abstract representation of objects (vertices) connected by links (edges). For questions about plotting data graphically, use the [data-visualization] tag instead.
1
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0answers
5 views
Removing Graph Nodes of a Specific Type and with Exactly Two Neighbors
Problem Description
I am working with an undirected, weighted graph. It contains two types of nodes, called "A-type" and "B-type". I am starting with a set of ...
1
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0answers
19 views
Minimum amount of edges that needs to be traversed to visit all vertices… or something like that
So I have this problem, where I'm given m connections over n vertices. The vertices are labeled ...
4
votes
1answer
36 views
Shortest path through a maze
I was trying to solve this problem in Java:
Given a 2-D array of black and white entries representing a maze with designated entrance and exit points, find the shortest path from entrance to exit, ...
1
vote
1answer
50 views
Creating a graph in Java
I'm building an application that implements the A* algorithm to calculate a route between two rooms. I am trying to create a graph which the algorithm can operate on and I am not sure if this is the ...
3
votes
0answers
55 views
Shortest path for every source-destination (s-d) pair in a network?
I am working on Dijkstra algorithm and trying to find the shortest path for every source-destination (s-d) pair in a network. I have the below code which is working fine.
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2
votes
0answers
15 views
Directed Acyclic Graph with topological sort
I have here a class which represents a directed acyclic graph (Graph) and a vertex in the graph (Vertex).
The vertices are ...
3
votes
2answers
40 views
Determining if there is a route between two nodes in a directed graph
This algorithm should return a boolean value, telling if there is a path between two nodes in a given directed graph.
...
2
votes
1answer
41 views
Improving time complexity of cheapest travel route algorithm
Below is the code to find the cheapest route for a passenger. stationsUnexplored is a Queue to which stations are added and ...
2
votes
0answers
27 views
Bidirectional Edmonds-Karp algorithm in Java
The Edmonds-Karp algorithm relies on breadth-first search in order to find an augmenting path in the residual flow network. This version of the algorithm uses bidirectional breadth-first search in ...
3
votes
0answers
38 views
Edmonds-Karp algorithm for maximum flow in Java [duplicate]
I have this implementation of Edmonds-Karp algorithm for finding maximum flow in networks. It runs in \$\mathcal{O}(VE^2)\$ time.
What do you think?
AbstractMaximumFlowFinder.java:
...
2
votes
0answers
23 views
Kruskal's algorithm in Java - follow-up
The previous and initial iteration at Kruskal's algorithm in Java
Now what I did is remove the fields and let the actual Kruskal-routine create the required data structures in the local scope, ...
2
votes
1answer
89 views
Dijkstra's algorithm in Python
I was hoping that some more experienced programmers could help me make my implementation of Dijkstra's algorithm more efficient.
So far, I think that the most susceptible part is how I am looping ...
3
votes
3answers
96 views
Pouring water between two jugs to get a certain amount in one of the jugs
I wrote a solution for a jug problem (given two jugs of water of different sizes find the steps needed to get specific amount of water in one of the jugs). I'm hoping for some input on my code. How ...
1
vote
4answers
339 views
Depth-first search in Python
I wrote this DFS in Python and I was wondering if it correct. Somehow it seems too simple to me.
Each node is a class with attributes:
visited: Boolean
...
1
vote
0answers
26 views
Max independent set of a sequence
This is the code I've written to find the maximum-weight independent set of a graph path. It's a standard problem with a well-known dynamic programming solution of linear complexity. Since it's a ...
4
votes
0answers
48 views
Finding cycles in a graph that pass through a vertex at most k times
I have a project that relies on finding all cycles in a graph that pass through a vertex at most k times. Naturally, I'm sticking with the case of k=1 for the sake of development right now. I've come ...
1
vote
1answer
55 views
Calculating Euclidean distance and performing unit-testing
The method creates a link, an edge between two nodes, and calculates the Euclidean distance.
I'm testing that after linking, the link does indeed exist, and that the distance is correct.
I've used ...
1
vote
1answer
90 views
What could I possibly change with this BFS and code to enhance its performance?
This code is supposed to find, in a graph, the node with the smallest maximum distance to all the other nodes. The problem can be found here.
For instance, in this example graph:
2 is the node ...
0
votes
1answer
34 views
Iteratively-Deepening Depth First Search (queue and non-queue)
I am aware that most 'generic' BFS algorithms that use a queue also check for uniqueness of visitation to 'speed things up' as it were, but I'm a bit unclear as to how to implement such a method as ...
5
votes
0answers
88 views
Graph implementation adjacency list 2.0
Version 1:
Graph implementation adjacency list 1.0
Please note the following:
All edges are directed
A user of the class Graph shall never be able to aces an object of type ...
2
votes
1answer
29 views
Parsing DAG from text
This module allows to parse indented text file into Map from node to child nodes identified by Coordinate. This module seems way ...
2
votes
1answer
44 views
Small generic path search framework in Java
I have this small generic path search library. It's not perfect at all, so I need some comments as to have a chance to improve it.
com.stackexchange.codereview.graph.model:
...
3
votes
2answers
103 views
Implementation of Dijkstra's algorithm to find the shortest path in graph
This is my implementation of Dijkstra's algorithm in C++.
Please clarify
Whether the class design is proper or if it needs to be improved.
I am just hard coding the vertex based on the priority of ...
2
votes
1answer
71 views
Optimizing for data import in Neo4j using py2neo
Here is my code for importing from a .csv to a neo4j graph using py2neo and cypher statements. I've noticed that it slows down significantly the bigger the graph gets. It takes several seconds just to ...
4
votes
0answers
78 views
Dijkstra's algorithm in PHP
This is Dijkstra's algorithm in PHP. Regarding the data structure, I use a 2-dimensional array $_distArr[m][n]=length to store it. Are there any improvements for ...
2
votes
1answer
77 views
Very slow graph walking
My code is very very slow. Could you give me hints on how I can make it much faster?
...
7
votes
2answers
154 views
Kruskal's algorithm in Java
I have this Java implementation of Kruskal's algorithm. It solves a tiny problem instance correctly, yet I am not quite sure, whether my implementation is correct.
The code as follows:
...
2
votes
1answer
150 views
Graph implementation adjacency list 1.0
Please note the following:
All edges are directed
Removal of edges/nodges is not implemented yet
A user of the class Graph can never (hopefully) access a ...
-1
votes
2answers
87 views
Cycles of pointers
I'm really inexperienced with cycles, so I want to make this code shorter. As far as I know, I've made a recursive cycle.
...
1
vote
0answers
29 views
A scalable function for get boundary vertices in a graph
Given a community division I need a list of vertices that have edges in more than one community, i.e., boundary vertices.
I've tried this:
...
7
votes
3answers
87 views
Removing equivalent authors in a list
I have a list of authors, where seeking duplicity. The indexes of these duplicates are stored in a list of lists named duplicity. For example, at index 0 in the list duplicity is nested list, which ...
1
vote
1answer
96 views
Minimum Spanning Tree using Prim's algorithm and an indexed minimum priority queue
I have written some basic implementation of a Minimum Spanning Tree using a indexed minimum priority queue.
For the implementation of the Priority Queue I used Sedgewick's Tutorials.
However, it seems ...
3
votes
1answer
1k views
Shortest path Dijkstra's algorithm
I'm trying to implement Dijkstra's algorithm to find the shortest path from a starting node to the last node of a 250px by 200px raw image file (e.g. starting node = [0][0], ending node = [250][200]). ...
3
votes
1answer
172 views
Prim algorithm implementation for adjacency list represented graph
Please review the implementation of Prim algorithm. Points on which I have doubt:
My Graph doesn't have any ID for nodes. Nodes are accessed based on their data. ...
1
vote
0answers
167 views
Kruskal algorithm implementation for adjacency list represented graph
Please review the implementation of Kruskal algorithm. Points on which I have doubt:
My Graph doesn't have any ID for nodes. Nodes are accessed based on their ...
3
votes
0answers
74 views
Djkistra shortest path implementation for adjacency list represented graph
Please review the implementation of Djkistra algorithms. Points on which I have doubt:
My Graph doesn't have any ID for nodes. Nodes are accessed based on their ...
2
votes
1answer
52 views
Extracting a subgraph
Given a huge graph, I want to traverse it, in the fastest way possible, and extract a subgraph with the following properties:
the starting node is specified
the maximum number of elements and max ...
1
vote
1answer
62 views
MinCostMaxFlow implementation is not fast enough
I'm trying to solve this problem:
A root tree is a directed acyclic graph that contains one node (root),
from which there is exactly one path to any other node.
A root tree is binary if ...
5
votes
2answers
222 views
Constructing a graph and performing a depth-first traversal
Please review the use of pointers and design in graph construction code and its depth first traversal. I haven't used smart pointers as I want to understand any issues in following implementation with ...
0
votes
3answers
338 views
Dijkstra in C++ to find shortest path for every vertex of a directed graph
I am trying to implement the Dijkstra algorithm in C++ that finds the shortest path for a graph from a text file. The text file contains a matrix that represents a directed graph.
What I am trying ...
10
votes
2answers
174 views
Is this Bridges code F# idiomatic?
Introduction
I'm primarily a C# programmer, just starting out with learning F#. I found myself with a problem which felt like it was appropriate for a functional language, and now that I have the ...
4
votes
1answer
155 views
Adjacency-list graph implementation in C++ (redone from scratch)
I had posted here before, but I decided that the approach used earlier - where every Vertex stores a vector of pointers to ...
0
votes
2answers
308 views
Optimizing Dijkstra implementation using PriorityQueue in Java
I am trying to make Dijkstra implementation more efficient. Below is the code for class Node which implements Comparable so it ...
3
votes
1answer
82 views
Improving efficiency of Prim's Algorithm
I have implemented Prim's Algorithm in Java. I am wondering how it can be made more efficient.
Below is the class Node for vertices.
...
4
votes
2answers
329 views
Minimum Spanning Tree using Prim's algorithm
I have implemented a Minimum Spanning Tree using Prim's Algorithm. Could someone give some about some improvements for code structure, conventions, performance, etc?
...
2
votes
2answers
97 views
has_cycle in directed and undirected graphs
I wrote a program that can tell if a graph has_cycle or not.
Can you please suggest more elegant and eloquent ways for this program?
(Perhaps better ways to represent a graph with vertices and ...
5
votes
3answers
490 views
Trip Advisor - Train routes
Gives advice to the user on which trains to take to reach a destination
...
5
votes
2answers
218 views
More optimized approach of Dijkstra's algorithm
I need a graph-search algorithm that is enough in our application of robot navigation and I chose Dijkstra's algorithm.
We are given the gridmap which contains free, occupied and unknown cells where ...
6
votes
1answer
145 views
Breadth First Search not SOLID enough v2.0
Here is a link to my original question:
Breadth First Search not SOLID enough
Here is my first attempt at refactoring. Instead of using a Tuple, I used a ...
5
votes
2answers
882 views
Graph vertex class implementation with adjacency lists
I wrote an implementation of a graph with each vertex storing a std::vector of vertices it's adjacent to.
Please critique this.
...
