# Tagged Questions

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11k views

### Usefulness of pre and post order traversal of binary trees

This may be very naive, but I was wondering, it the context of binary trees (plain, sorted and balanced), of all the traversal types: depth-first pre-order depth-first in-order depth-first post-...
257 views

### Graph theory problem (name unknown)

I am trying to solve the following kind of problem. I do not know if there is already a name for this, or a solution; however, I'm willing to bet there is. I was hoping someone could point me in the ...
705 views

### Finding an A* heuristic for a directed graph

In a previous question, I asked about finding a route (or path if you will) in a city. That is all dandy. The solution I chose was with the A* algorithm, which really seems to suit my needs. What I ...
453 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 ...
229 views

### Heuristic Approach for Flexible DIFF Implementation

I have created a DIFF implementation to compare document revisions at work. It is based on An O(ND) Difference Algorithm and Its Variations. One thing that has become important is to take the list ...
1k views

### Finding most Important Node(s) in a Directed Graph

I have a large (≈ 20 million nodes) directed Graph with in-edges & out-edges. I want to figure out which parts of of the graph deserve the most attention. Often most of the graph is boring, or at ...
154 views

### In a mutual credit network, how would you program an automatic jubilee?

A little explanation might be needed. I mean mutual credit the way that it's defined here: a type of alternative currency in which the currency used in a transaction can be created at the time of ...
140 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 ...
4k views

### Is Pre-Order traversal same as Depth First Search?

It seems to me like pre-order traversal and DFS are same as in both the cases we traverse from root till the left branch and back to root and then to the right branch recursively. Could any please ...
175 views

### Mutation operator for genetic algorithms for solving traveling salesman problem

I need help help for defining mutation operator for traveling salesman problem. I'm currently using this now (pseudocode): mutate ( strand ): for n in random_interval ( min_gene_index, ...
214 views

### Is this Wikipedia pseudocode for in-order generic tree traversal correct?

Wikipedia states that the following algorithm works for any tree (not necessarily binary trees) Perform pre-order operation For each i (with i = 1 to n) do: Visit i-th, if present ...
988 views

I thought I was doing breadth-first graph search correctly, but my instructor's grading script is telling me that my answer is incorrect. From the instructions: Consider a breadth-first graph ...
121 views

### How to calculate number of indirect dependencies of a class?

Most of the static code analysis tools which analyse class dependencies generate dependency pairs of classes where each pair represents a direct dependency between two classes. Given those dependency ...
3k 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 ...
1k views

### Architecture for Social Graph data that has a Time Frame Associated?

I am adding some "social" type features to an existing application. There are a limited # of node & edge types. Overall the data itself is relatively small (50,000 - 70,000 for each type of node)...
450 views

### Graph traversal and filtering in indoor navigation and path finding

Which of the following options take less processing time/is less expensive in a graph traversal algorithm for a (indoor)navigation system? a) To produce all possible paths between start and ...
832 views

### Understanding Tarjan's Bridge-finding algorithm

Tarjan's algorithm for finding bridges in a graph is found here: http://en.wikipedia.org/wiki/Bridge_(graph_theory)#Tarjan.27s_Bridge-finding_algorithm. However, I don't understand the condition for ...
383 views

### Improving the running time of Breadth First Search and Adjacency List creation

We are given an array of integers where all elements are between 0-9. have to start from the 1st position and reach end in minimum no of moves such that we can from an index i move 1 position back and ...
41 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 ...
661 views

### Languages with graph data structures and algorithms in standard library

I am trying to improve my knowledge and ability with graphs and graph algorithms and have noticed something curious: as far as I can tell no "mainstream" language contains support for graphs in its ...
589 views

### how to traverse towards child node from parent node in n-ary tree? [closed]

In an n-ary tree... Given a reference to some child node And a reference to a distant parent of the referenced child node Is there a method that a parent node can use to figure out which of its ...
1k views

### Looking for an algorithm to connect dots - shortest route

I have written a program to solve a special puzzle, but now I'm kind of stuck at the following problem: I have about 3200 points/nodes/dots. Each of these points is connected to a few other points (...
288 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 ...
176 views

### City exploration algorithm

The purpose of the algorithm is to create n routes on a geographical map, where n is being given, whereas all routes take no longer than t time units by foot and end where they start, while trying to ...
1k views

### Gremlin — do I have to know Java/Groovy

This is the excerpt from the project's Github page. Gremlin provides graph traversal related syntactic sugar to Groovy. Groovy provides dynamic language syntactic sugar to Java. Realize that ...
89 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] ... s[2,...
293 views

### Algorithm for searching the neighbors neighbor of a directed graph

Is there an algorithm to search a directed graph (tree) for its neighbors neighbor? My current brute-force solution works as follows: for each node n: for each child c of n for each parent ...
917 views

### What graph traversal algorithm should I use?

I would like to write an algorithm which can traverse a graph and hopefully later I can implement it to use for an indoor navigation system. The graph would come from floor plans of a building and ...
50 views

### The maximum number of induced cycle in a simple directed graph

Given a simple directed graph G=(V,E) an induced cycle is a cycle where no two vertices of the cycle have an edge that is not in the cycle. (Chordless cycles are induced cycles with at lease 4 ...
187 views

### How to avoid loop in a dept-search in a graph?

I must implement , in Lisp , a depth-search algorithm in an implict graph (namely a graph where I have the starting node, the goal node, and the successor function ,f, that give a node create his ...