Questions tagged [programming-challenge]

Programming challenges are off-site challenges meant to offer programmers educational experiences while testing their abilities.

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Convert a hex string to base64

I wrote a program that converts a hex-encoded string to base64. It's my solution to the first of the Cryptopals challenges. My main concerns are: Portability. I don't want to rely on implementation-...
73 views

LeetCode - Merging piles of stones

This is a LeetCode Problem You have a pile of stones presented as an array. On each turn you must merge k consecutive piles of stones, starting from any pile you wish. You must continue merging ...
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LeetCode: Merge k sorted lists C#

https://leetcode.com/problems/merge-k-sorted-lists/ Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity. ...
110 views

(Project Euler #1) Find the sum of all the multiples of 3 or 5 below 1000

I have decent experience in programming before (mostly C++), but I am very, very, very new to Python, and I decided to try out Project Euler as an exercise. Here's the description of Problem 1: If ...
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Counting block combinations I: Project Euler 114

Problem statement (For more detailed description (including pictures), please, visit the link): A row measuring seven units in length has red blocks with a minimum length of three units placed on ...
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Counting Bouncy Numbers: Project Euler #113

Problem statement: Working from left-to-right if no digit is exceeded by the digit to its left it is called an increasing number; for example, 134468. Similarly if no digit is exceeded by ...
924 views

Project Euler problem #112

Problem statement: Working from left-to-right if no digit is exceeded by the digit to its left it is called an increasing number; for example, 134468. Similarly if no digit is exceeded by ...
58 views

Project Euler 121

The following code solves Project Euler Problem 121. I will quote the description of the problem A bag contains one red disc and one blue disc. In a game of chance a player takes a disc at random ...
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Find the smallest positive integer that is absent from a given array

I made the acquaintance of big-O a couple of weeks ago and am trying to get to grips with it, but although there's a lot of material out there about calculating time complexity, I can't seem to find ...
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Translate English to Pig Latin

This is a program for converting English to the pseudo-language Pig Latin. Not the strictest form of Pig Latin but it most likely will accurately output an argument in Pig Latin. I got the idea from a ...
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Project Euler Problem 45

As a self-teaching Python beginner for almost 4 months, I have mostly been doing online challenges including Project Euler problems. Problem 45 asks: Triangle, pentagonal, and hexagonal numbers ...
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LeetCode: Binary Tree Zigzag Level Order Traversal C#

https://leetcode.com/explore/interview/card/top-interview-questions-medium/108/trees-and-graphs/787/ Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from ...
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Twelve Days of X-mas in Python

Printing the lyrics of "Twelve Days of Christmas" seems to be a fairly popular programming challenge. As I've successfully attempted it, I was wondering if the code can be simplified even further (...
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LeetCode #494: Target Sum (Python)

Below is my solution to LC #494: Target Sum (given a list of numbers and a target integer, find out how many different ways the numbers can be subtracted from the total sum to result in the target sum)...
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Codewars - Highest Scoring Word

Here is my solution for CodeWars - Highest Scoring Game Given a string of words, you need to find the highest scoring word. Each letter of a word scores points according to its position in the ...
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Counting numbers that are divisible by 3 and can be produced from the digits of a given number

I'm trying to solve this problem from codewars. Problem Given a certain number, how many multiples of three could you obtain with its digits? Suppose that you have the number ...
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Python Method for Text Input from Project Euler

Method Frequently input for problems is given as a 1D or 2D array in a text file. Have knocked out a method to do so, but believe something shorter, clearer and cheaper can be written: ...
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Challenge: MORSE_CODE.PY

Converting words to morse code and vice versa using dictionaries and that's it. ...
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Counting the triangles that can be formed from segments of given lengths

Problem Statement: Given an unsorted array of positive integers. Find the number of triangles that can be formed with three different array elements as lengths of three sides of triangles. ...
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Calculate the rates at which users get stuck at each stage

I completed an algorithm problem just as a personal study, and I can't help but feel like my solution is a bit needlessly complicated, although I can't figure out a better way to do it. Here's the ...
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Expanding powers of expressions of the form ax+b

I solved the following problem: Write a function expand that takes in an expresion with a single, one character variable, and expands it. The expresion is in the form ...
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Convert a Binary Tree to Doubly Linked List

Challenge Link on geeksforgeeks: Binary Tree to DLL Given a Binary Tree (BT), convert it to a Doubly Linked List(DLL) In-Place. The left and right pointers in nodes are to be used as previous ...
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Immediate Smaller Element Time Limit Exceeded

Immediate Smaller Element The code is working fine Code is here. For each element in the array, check whether the right adjacent element (on the next immediate position) of the array is smaller. If ...
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Introduction to Haskell: Validating credit card numbers

I have implemented the introductory challenge of University of Pennsylvania's CIS 194: Introduction to Haskell (Spring 2013) course. I have added the most important information of the problem ...
407 views

LeetCode: Group Anagrams C#

LeetCode: Group Anagrams C# Given an array of strings, group anagrams together. ...
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Forming words that start with consonants and vowels

I am just starting to learn programming. I had already coded some functions and stuff in other languages, and whilst trying to complete this Python challenge Kevin and Stuart want to play the 'The ...
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LeetCode: Pascal's Triangle C#

https://leetcode.com/explore/interview/card/top-interview-questions-easy/99/others/601/ In Pascal's triangle, each number is the sum of the two numbers directly above it. Example: ...
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Custom Knight dialer solution's time and space complexity

I recently solved the Knight Dialer problem but I'm not quite sure if I got the time complexity right; hence I'm requesting the following: 1) Time and space complexity review and explanation on why ...
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Find minimum number of rooms required

Problem statement is as follows Given an array of time intervals (start, end) for classroom lectures (possibly overlapping), find the minimum number of rooms required. For example, given [(30, ...
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C++ For Euler Problem 3

Here's my solution for Euler Problem 3: The prime factors of 13195 are 5, 7, 13 and 29. What is the largest prime factor of the number 600851475143 ? I'm using the Euler problems to learn ...
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Rotate List by K places

I am trying to solve the question at :https://leetcode.com/problems/rotate-list/ Question: Given a linked list, rotate the list to the right by k places, where k is non-negative. Example 1:...
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LeetCode #37: Sudoku as Exact Cover Problem solved using Dancing Links

Introduction I provide a regular 9x9 Sudoku solver, reducing the puzzle to an Exact Cover Problem. The algorithm used is Knuth'...
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Project Euler # 62 Cubic permutations in Python

The cube, 41063625 ($345^3$), can be permuted to produce two other cubes: 56623104 ($384^3$) and 66430125 ($405^3$). In fact, 41063625 is the smallest cube which has exactly three permutations ...
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Project Euler Problem #50 Consecutive Prime Sums

Problem: Which prime, below one-million, can be written as the sum of the most consecutive primes? At the moment my code runs for over 200 seconds and was wondering how I can find a way to bring that ...
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Find the first missing positive integer in an array of integers

The problem is the one explained in Given an unsorted integer array, find the first missing positive integer Given an unsorted integer array, find the first missing positive integer. For ...
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Banking application for Udemy Java course

I just "finished" a Udemy Java that involves building a banking application. Here is the problem definition: Scenario: You are a back-end developer and need to create an application to handle new ...
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How can I make my solution to “Climbing the Leaderboard” not time out?

I tried to solve the following challenge and optimize the solution but my code still times out. My code is below. Problem statement Climbing the Leaderbord Alice is playing an arcade game and ...
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Leetcode Finding Maximum Area of Island Solution

Given a non-empty 2D array grid of 0's and 1's, an island is a group of 1's (representing land) connected 4-directionally (horizontal or vertical.) You may assume all four edges of the grid are ...
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Sum Square Difference, which way is more Pythonic?

I'm using python 3 and I am creating an algorithm to find the sum square difference for the first 100 (or 1 to x) natural numbers. This happens to be project euler problem 6 if anyone is wondering. I'...
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Project Euler #5 Optimized

I have seen multiple questions on this problem but none seem to answer my specific question. To start, the basic question is asking to find the smallest number that is divisible by numbers 1 to 20. ...
185 views

LeetCode: Linked List Cycle

Challenge https://leetcode.com/explore/interview/card/top-interview-questions-easy/93/linked-list/773/ Given a linked list, determine if it has a cycle in it. To represent a cycle in the ...
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Code Challenge: basic arithmic operations using only incrementation operator

Challenge Write a function that takes 2 integer operands left and right (both >= 0) and evaluates one of the following ...
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Project Euler # 15 Lattice paths in Python

Starting in the top left corner of a 2×2 grid, and only being able to move to the right and down, there are exactly 6 routes to the bottom right corner. How many such routes are there through a 20×20 ...
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Project Euler # 11 largest product in a grid in Python

In the 20×20 grid below, four numbers along a diagonal line have been marked in red. The product of these numbers is 26 × 63 × 78 × 14 = 1788696. What is the greatest product of four adjacent numbers ...
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Hex string to Base64 in Haskell

This is my take on the first challenge on the cryptopals crypto challenges list. I think that i made it quite simple but i feel like it is possible to optimize it further. Any suggestion? The code: ...
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Least Recently Used Cache Daily Coding Practice

I have the following challenge problem for which I was able to get a solution working, but not in $O(1)$ time as the problem asks for. Could someone point me in the right direction to optimize this?...
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Solution to 3Sum problem on Leetcode using HashTable

The problem of 3sum is described as: Given an array nums of n integers, are there elements a, b, c in nums such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero....