A data structure is a way of organizing data in a fashion that allows particular properties of that data to be queried and/or updated efficiently.

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Create ranges from an array of integers

Given an array of ints, return a string identifying the range of numbers Example Input arr - [0 1 2 7 21 22 1098 1099] Output - "0-2,7,21-22,1098-1099" . Is there any improvement possible in this ...
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1answer
67 views

Determine the index where two lists diverge

Background A class provides an API to determine the index where two string lists diverge. ...
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2answers
63 views

Check is_permutation on a pair of same sized arrays

After considering the suggestions of my previous question Check whether given a pair of arrays are permutation of each other, I changed the code. Resolved the bug reported earlier In place of ...
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3answers
211 views

Check whether given a pair of arrays are permutation of each other

Check whether two given arrays are permutation of each others. Does this implementation guarantee execution of \$O(n)\$ time? What is the additional space utilization for this implementation by ...
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1answer
62 views

Object pool with linked list of available objects implementation

I was reading some gameprogrammingpatterns (awesome book, by the way, would recommend) and was very excited when I learned that unions are a thing that exists, so I decided to implement an object pool ...
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63 views

Create pairs from a set of numbers

Problem here is to list all pairs from a set of integers. We need 2 versions. In the first program, the order matters — pairs (a,b) and (b,a) are considered distinct. In the second program, (a,b) and ...
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2answers
34 views

Univariate polynomial multiplication using Doubly Linked List

A univariate polynomial is a polynomial over a single variable, and in the following discussion when we say polynomial, we mean a polynomial in a single variable. You are given two polynomials ...
7
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1answer
59 views

Growing my own Tree (Structure)

Summary VB6 doesn't have a great selection of data structures to work with, so again I find myself creating my own. I have a need to dynamically generate a directory structure on the file system. The ...
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2answers
79 views

Simple binary heap in C#

I've written a simple binary heap in C# and I want to know if it has any problems or if I can make it better. ...
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1answer
285 views

Quadtree implementation

I've implemented a quadtree in C++. Ignore any apparent similarity to the pseudocode on Wikipedia, it's all in your head, I swear. How can I improve? Algorithm speed/space improvements, any extra ...
2
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1answer
76 views

Binary Search Tree in C

I have implemented a BST from scratch. My aim is to draft better code and understand some pitfalls which I may have overlooked. It includes the following functionalities: Insert a new item. Find ...
8
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1answer
91 views

Java Trie structure

I recently have been working on a Trie in Java. I have looked at the related posts here on Code Review to try and enhance my code, but I do have some methods and constraints not present on other ...
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1answer
94 views

Constructing and maintaining a complete binary tree

Problem statement: Create and maintain a Complete Binary Tree in C. Include the following operations. Insert a given key and perform inorder Replace ALL occurrences of the given key ...
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2answers
602 views

Designing another Coffee Machine Application

After reading Designing a coffee machine yesterday, I decided I could also give the same problem a try. I have used the following problem statement (copied from the given question): Design a ...
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1answer
74 views

3-stack implementation with a single array

I'm teaching myself data structures and would really appreciate some feedback on my stack implementation. A couple of things I'm not sure if I should be doing: creation of the array and pointer ...
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5answers
3k views

Designing a coffee machine

I was recently rejected from what looked like a really promising string of interviews. I did very well in a questionnaire style review, and then they handed me this assignment (more or less): ...
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0answers
17 views

Entering base characters one-by-one for a List [closed]

This function should prompt the user to enter bases characters (a, g, c and t) one-by-one and then insert them in the List. ...
6
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2answers
388 views

C++ Linked List Implementation

I'm learning C++ and also about data structures, so I am trying to implement some. This is my linked list. I've included two different ways of getting the length of the list, with a ...
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5answers
757 views

Singly Linked List in Java

I created my own implementation of a Singly Linked List. Is there anything I can improve on, in terms of effciency. Also, what other methods would you recommend for me to try and implement. My goal is ...
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0answers
40 views

Extract and rename specific columns of a CSV data file

I have a CSV data file with 3,896 columns (variables), and I am attempting to extract a particular subset of columns for use in a data analysis project. To avoid the burden of having to constantly ...
6
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1answer
51 views

Prefix trees for auto suggest

I wrote a quick prefix tree implementation. I know it may be far from perfect, but I need to make sure that I got the basics right. My main concerns are: Have I settled for the correct data ...
3
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1answer
129 views

Depth First Search and Breadth First Search in C++

I am trying to learn DFS and BFS. However, I just want to make sure that I am not doing anything wrong. Would you please determine if the BFS and DFS functions are correct? ...
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171 views

Return list of common email ids from a list of lists

Input: ArrayList of ArrayLists with email ids. Output: Return ArrayList of email ids which appears in each inner ArrayList. Ex: Input: [[abc@gmail.com, ...
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3answers
97 views

Finding all integers in an array with odd occurrence

I am doing an interview exercise problem from here. The problem is to find "all numbers that occurred an odd-number of times in an array". Here is my high level psuedo code thinking: Construct a ...
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1answer
54 views

Data structure for inserting and replacing data in list

I have a list of key value pairs, that is used as an intermediate store for building URL parameters or JSON data. Currently this is done with a linked list: ...
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1answer
42 views

Perceptron algorithm

This is the Perceptron algorithm, I wrote this implementation with my friend. It gets the job done, but it's quite dirty, perhaps one of you stylish hackers might help me beautify this beast. This ...
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4answers
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Smart as a bag of rocks

For my second project in CS2, I was given the following assignment: Implement a new ADT called a bag with receipts. The specification for the class of bag with receipts differs from a ...
3
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1answer
85 views

Trie Implementation in Java

I am trying to implement a Trie class in Java which just supports insertion and searching operation up until now. I think it works perfectly on the several examples ...
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0answers
63 views

Memory Segmentation Simulation

I recently have been working on a project to simulate segmentation in memory. I wanted to create everything from scratch; not use pre-built data structures. I create a memory object that allows for ...
2
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0answers
60 views

Linked list order reverse program efficiency

Here is my function which convert linked list in the following order: Example: Inputs: 1->2->3->4->5->6->7->8->NULL and k = 3 Output: 3->2->1->6->5->4->8->7->NULL. Code: ...
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110 views

Check if a binary tree is balanced

Looking for code-review, optimizations and best practices. This question is attributed to geeksforgeeks. NOTE: Please help me verify space complexity, as I am creating ...
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1answer
46 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 ...
5
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0answers
53 views

BiDirectional Dictionary (and its Mutable friend can come too)

I've attempted to implement a 1-to-1 dictionary in Objective-C. I'm probably missing some convenient methods that one might commonly want to use. These are both declared in the same ...
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2answers
154 views

Is there some way of taking advantage of code reuse in this example?

I am implementing a set, using an array as the backend. Here is how I declared it (and some method implementations): ...
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1answer
57 views

Disjoint-set data structure in Python 3

Inspired by this question, I decided to implement a Disjoint-set data structure in Python 3. I mainly followed this description for understanding the algorithm (but did not do the optimizations for ...
2
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2answers
122 views

Bag data structure (a set that can store multiple copies of items)

I am trying to make my class a bit cleaner, especially some of its methods like Count, __add__, ...
2
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4answers
79 views

Coupon collector

This is a coupon collector code to analyze the running time. I need some suggestions on improving the running times of this code. I have used the data structure dictionary, but is there any other data ...
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2answers
113 views

Inefficient hash map operation provokes OutOfMemory: Java heap space error

I know I can increase the size of the heap but that seems like a poor solution. This program runs correctly on small files but when run on large data sets it crashes with the OutOfMemory: Java heap ...
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3answers
488 views

Finding duplicates in two sorted arrays

This is an interview question from here. Specifically, the second asked for a function that took in two sorted arrays of integers with no duplicate values within a single array and which returned an ...
5
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2answers
151 views

Data structure to count occurrences of entries

I would love to hear any thoughtful suggestions on how to improve my programming style in order to be more understandable. Listed below is a sample of my code which I wrote in Eclipse: ...
4
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1answer
66 views

Design/reiterate or code reuse for linked list

This is what my class hierarchy looks like. I have an abstract superclass, AbstractLinkedMyList, that contains common operations for both sorted and unsorted linked ...
15
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1answer
264 views

Order a delicious pie here

For a quick summary: I've created this internal web application, and I've hit a point where I can really see the mess I've made. I need some help separating the logic, the view, and the data. More ...
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1answer
65 views

Rewriting linked list function without a NULL variable

This is how my LinkedList class looks like in PHP. I am trying to figure out if I can rewrite my reverse_list_recursively() ...
3
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3answers
122 views

Implementing a singly LinkedList and IList interface

I have implemented a LinkedList in C#. What would you change/make better? What naming conventions are misused? What would you add? Some of my ideas are to make it ...
3
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1answer
71 views

Least common ancestor (LCA) in a binary tree

Find the LCA in binary tree, where a node is also its own ancestor. This question is attributed to GeeksForGeeks. I'm looking for code review, optimizations and best practices. ...
3
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1answer
118 views

Finding the shortest substring containing keywords

Problem: Write a function that takes a String document and a String[] keywords and returns the smallest substring of ...
7
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4answers
511 views

Recursive binary search tree - follow-up

This is a follow-up to Recursive binary search tree changes: Used raw pointers rather than std::unique_ptr const correctness Made variable names more beautiful implemented at() How can I improve ...
4
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3answers
566 views

Preorder, inorder, postorder for tree in C++11

Please review my code for preorder, inorder and postorder of a tree. I am using C++11 (or wanted to use), so let me know if anything is deviating from the C++11 standard. ...
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Hash Table Implemented by Javascript

I recently tried to implement a simple hash table using Javascript. Could anyone help me review my implementation? ...
2
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2answers
118 views

Counting a cycle

An interview question I got - Each element of an int array points to the another element, eventually creating a cycle. Starting at ...