a mathematical structure that contains a collection of vertices or 'nodes' and a collection of edges that connect pairs of vertices

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55 views

Decision making algorithm

I'm currently solving an optimisation problem of my own design, just to experiment and learn a little something. Here's the concept: I have a user that starts at home. The objective of this user is ...
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0answers
58 views

Algorithm to generate Edges and Vertexes outwards from origin with max multiplicity of 3

I am creating a 2d game for a website where the universe can grow extremely large (basically infinitely large). Initially, the universe is composed of 6 stars that are an equal distance from the ...
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39 views

Graph grouping with criteria

I start with a list of adjacent tetrahedra, where there are tight seals to one another along faces for two tetrahedra that are adjacent. The vertices belonging to these faces for both tetrahedra are ...
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1answer
115 views

Single Source Shortest Path

In the lecture we are taught that we can solve All Pairs Shortest Path(APSP) with matrix multiplication. In APSP we are creating a distance table for all the distances between each nodes in the ...
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2answers
309 views

Workaround for implementing operations on doubly linked or circular data structures in languages with immutable data

I would like to learn how to make graphs and perform some local operations on them in Haskell, but the question is not specific to Haskell, and instead of graphs we may consider doubly linked lists. ...
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2answers
240 views

How to optimize/parallelize the following clustering/joining algorithm:

I have relatively-small algorithm that takes up ~60% of the total run-time of my scientific code (57 lines of 3600), so I would like to find a way to optimize what I'm doing and make the code ...
3
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1answer
87 views

Are these graph coloring algorithms equivalent?

Suppose you want to color the vertices of a graph in a greedy fashion, given a predetermined order of these vertices. The goal is to avoid giving two adjacent (linked by an edge) vertices the same ...
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1answer
130 views

undirected c++ graph with a direction [closed]

I want to create a Graph in C++ that has directions, with directions I don't mean the direction of an edge but what I want is an undirected graph where the edges have a direction to the next vertex, ...
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0answers
66 views

Belman-Ford 2d array variation problem

I've got a problem with applying a Bellman-Ford algorithm to 2D Array (not to graph) Input array has m x n dimensions: s[1,1] s[1,2] ... s[1,n] -> Exit s[2,1] s[2,2] ... ...
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33 views

Filter out noise in line graphs

I have a question regarding finding relevant events in a line graph. The following graphs show the views (y-axis) of a video over time (x-axis). Certain events lead to an huge increase in views and ...
2
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1answer
185 views

Dependency ordering algorithm of a compiler

Let's say, hypothetically, I'm writing a Java compiler. And we assume that in my case a class can't be fully compiled until all signatures of dependencies (imports and other used classes) are known. ...
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1answer
44 views

How an add vertex operation could be performed in constant time for a graph represented using adjacency list?

Adding a vertex in a graph that is represented using an adjacency list takes O(1) time complexity according to http://bigocheatsheet.com/ (graph operation > adjacency list > add vertex). It is said ...
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1answer
140 views

why adding a vertex in a graph represented using an adjacency matrix takes O(|v|^2) time complexity?

Adding a vertex in a graph that is represented using an adjacency matrix takes O(|v|^2) time complexity according to http://bigocheatsheet.com/ (graph operation > adjacency matrix > add vertex). But ...
2
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1answer
141 views

Does a tree node have an ancestor?

Below is a rooted tree, where any node C except root has one parent P Ancestors of a node C are the nodes on path from C to root, including P,P's parent,P's grandparent, .... till root. My ...
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0answers
92 views

Approaches to Modeling a Graph Database over the Google App Engine Datastore?

I want to model a graph database over the Google App Engine Datastore. I am currently working on creating a Link entity to model the concepts of link/edge/relationship to the graph of objects. I am ...
2
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1answer
100 views

Efficient algorithm for hierarchical traversing? JSON hydration, for example

I'm writing a small library that helps you hydrate JSON data into objects. Given this JSON example: { "date": "1970-01-01 00:00:00", "foobar": "baz", "user": { "name": "foobar", ...
3
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1answer
200 views

Finding the optimal root

I am trying to solve a quora hackathon challenge question. The question descrpition is as follows : For the purposes of this problem, suppose Quora has N questions, and question i (1≤i≤N) takes ...
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1answer
33 views

How can I avoid needing to check for the existence another vertex when adding to an adjacency list?

I'm writing a Graph, and decided to make the Adjacency List its own class. Right now, (stripped down) it looks like this: public class AdjacencyList<Vertex> { //A map between a vertex, ...
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4answers
91 views

How definite of an order is there to a depth-first search of a graph?

I have the following graph that I need to simulate a depth-first search of; starting at g: My question is: How definite of an order is there when performing a depth-first search? When doing a DFS of ...
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2answers
220 views

Algorithm to find the optimal trade route (negative cycle with lowest cost per edge in a digraph)

Given the following problem (a slightly simplified description of trading in the computer game Escape Velocity: Nova (system map)): Given a set of (solar) systems. Each system is connected by ...
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1answer
99 views

Graphs and minimum spanning trees?

I am having a hard time finding information on how Graphs and spanning tree's work and how to construct/structure them. The reason is that I'm using a Delaunay Triangulation algorithm within the ...
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0answers
49 views

Graph curve and actual curve plotted on screen implementation patterns

I'm implementing a graph plotter. There are Curve objects, that contains points of actual XY data. When I plot to screen, I need to calculate the XY points on screen, resulting a PlottedCurve. This ...
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1answer
234 views

How to implement efficient heterogeneous microservice data queries?

Our team has an idea of implementing a simple declarative DSL that would let users query the enterprise's domain model via a single interface without caring which specific microservices to call to get ...
4
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1answer
161 views

Algorithm to find whether there is a path (any path) above length X between two vertices

We all know how to find the shortest path between two vertices, but what if I just want to know the answer to this question - is there a path, (any path), between vertex A and B of length larger than ...
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0answers
60 views

algorithm for group reassignment of points

I have a list of clustered points but they are not in the cluster which has the center closest to them. The objective is to reassign them to minimize the total distance of each point to its cluster ...
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1answer
204 views

Graph visualization algorithm

I need a 2d or 3d graph visualization algorithm by which adding/removing a node or a relationship does not have a butterfly effect on the positions of other nodes. (We are talking about a directed ...
5
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1answer
183 views

What is the maximum number of steps to find a bug using bisecting?

Assume that a node A in the commit tree of a codebase contains a bug but some ancestor B of A is clean from that very bug. Given the topology of the commit tree [B,A] leading from B to A, can we ...
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1answer
51 views

Render order of two-edge directed node graphs

I'm trying to find an algorithm for graphs with the following contents: Nodes with no edges leading out of them (shown here as a red circle) All other nodes have exactly two edges leading out ...
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69 views

All clustering possibilities for a graph

Is there a known algorithm for finding all clustering possibilities for a directed graph? EDIT: By cluster i mean a weakly connected sub-graph G, so that E(G) > 0. By a clustering possibility I ...
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0answers
47 views

Domination algorithm in graphs

I'm working on a project, on an app, that can visualize undirected graphs and show on this domination algorithm. There are some examples: I have some open questions about programmable solution of ...
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2answers
262 views

Big graph traversal with OOP

I'm trying to solve a algorithmic contest's problem. I have a matrix 2000x2000. I want to represent it as graph and traverse it with BFS/DFS. I have time limits on app running (2s). Simple vertices ...
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3answers
349 views

Algorithm or domain for finding cheapest subgraphs that connect vertex pairs

I am currently working on a project inspired by the Ticket to Ride board game. This board game is played on an undirected graph where each vertex represents a city and each edge represents a ...
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1answer
197 views

Connected components of undirected graph

Suppose I have an undirected graph G with vertices v1...vn and edges. Right now it is in adjacency list representation. For every time moment I have as input some subset of vertices that are "active" ...
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0answers
50 views

Codeforces : 505C. Mr. Kitayuta, the Treasure Hunter

Question : Is the attached logic correct? I am asking since my code based on this logic failed. Here is the problem link. Reproducing here verbatim : The Shuseki Islands are an archipelago of ...
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1answer
360 views

Is there some structured format for drawing source control branching diagrams?

Everyone on my team draws branch diagrams differently, including how branches exit or reintegrate to the parent, how cherry-pick merges are shown, and a host of other aesthetic choices. Is there some ...
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1answer
255 views

Why does this algorithm work in O(n m)?

This is from a blog post on Codeforces. I couldn't really understand why the editorialist goes on to claim that this code works in O(n m) This is a graph problem, where we are supposed to find the ...
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2answers
254 views

Why does this implementation of Dijkstra's algorithm work in O(n^2)?

Here is the code I use for implementing Dijkstra's algorithm. Consider a graph with n vertices and m edges. Shouldn't it run in O(n^2 m) ? Someone may say that there are n vertices and each edge gets ...
4
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1answer
121 views

Mathematically correct A* heuristic / distance estimator for a latitude / longitude graph

I have a graph in which each node is a geographical point on the surface of the earth, defined by it's latitude / longitude coordinates. Correct ways to calculate the distance between two such points ...
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1answer
122 views

Setting and getting values from a x-y graph

I have a bunch of x-y graphs given to me and I need to be able to transform them into some kind of data structure from which I will be able to get Y with X value. The problem is, though that I have 4, ...
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1answer
213 views

What is the minimum cost graph inside a strongly connected component, which connects every vertex?

So for MST there are 2 possible definitions in an undirected graph. Keep in mind that in an undirected graph the MST algorithm always has n - 1 edges and no cycles. In an undirected graph, it doesn't ...
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2answers
248 views

Merge directed acyclic graphs minimizing number of nodes

I have some DAGs (directed acylic graphs) and I want to merge them in order to minimize the number of nodes (we could say that every node has a cost, while edges are free). These four different DAGs ...
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7answers
893 views

How do you unit-test code using graphs?

I am writing (recursive) code that is navigating a dependency graph looks for cycles or contradictions in the dependencies. However, I am not sure how to approach unit testing this. The problem is ...
2
votes
2answers
323 views

Finding shortest path between nodes with a twist

Note: if you feel that I should include code, please tell me. I am solving a problem of finding shortest path between nodes. I am given the vertices between nodes, however they are one sided (ie you ...
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1answer
228 views

Find 'Connected Components' in undirected, unweighted graph coded as a 2d array

Given an undirected, unweighted graph coded as a 2d array, how can I find the number of different connected components? Example There is the following 2d array (I'm not putting any brackets to ...
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1answer
339 views

Number of sequences when no adjacent items can be the same

I came across this one problem, There is a particular sequence only uses the numbers 1, 2, 3, 4 and no two adjacent numbers are the same. Write a program that given n1 1s, n2 2s, n3 3s, n4 4s ...
4
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1answer
455 views

Shortest Path Between Two Nodes in a +10 Million Nodes Graph

I have my own knowledge graph representation, read from ConceptNet and NELL, containing tens of millions of nodes in which I want to calculate the nearest distance (if any) between two concept nodes. ...
4
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1answer
363 views

Data structures and algorithms for a directed rooted tree with inherited properties?

I need to represent a directed rooted tree in memory. The caveat is, that nodes have properties. And those properties are inherited (but not 100%) by the child nodes, recursively. What would be a ...
2
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1answer
257 views

Find n nodes farthest away from each other

I'm looking for an algorithm that gives me the n nodes that are the farthest away from each other. Can this be accomplished relatively efficiently? To clarify my question: I think of the problem as ...
3
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2answers
432 views

How can I find the shortest path between two subgraphs of a larger graph?

I'm working with a weighted, undirected multigraph (loops not permitted; most node connections have multiplicity 1; a few node connections have multiplicity 2). I need to find the shortest path ...
2
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4answers
2k views

Finding the shortest path through a digraph that visits all nodes

I am trying to find the shortest possible path that visits every node through a graph (a node may be visited more than once, the solution may pick any node as the starting node.). The graph is ...