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

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Printing staircase revisited

What can be more elegant ways to solve the given problem. # ## ### #### Code: ...
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1answer
24 views

Sum of all paths between all pairs of nodes in a tree

I'm trying to solve a competitive programming problem. It basically gives a undirected graph (tree-like: no multiple paths between two nodes...) and asks for the sum of all possible paths between any ...
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1answer
12 views

Encoding and decoding in Haskell — 99 Problems exercise 13, 14

I've been working on these solutions to the Haskell 99 questions, encoding and decoding series for a while now, so I figured I ought to present them to see how I screwed up the implementation. ...
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1answer
24 views

Finding longest common prefix

I have been trying to solve a modification of the Longest Common Prefix problem. It is defined below. Defining substring For a string P with characters P1, P2,…, Pq, let us denote by P[i, j] ...
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1answer
22 views

Hackerrank Sparse Arrays in Swift

I solved this problem and was looking for feedback on my code. More efficient, cleaner, more verbose variable names, anything helps. There are N strings. Each string's length is no more than 20 ...
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2answers
906 views

Morse Code Conversion

Challenge Write a program which reads a file containing Morse Code and outputs the conversion. Specifications The first argument is a path to a file. The file contains multiple lines. Each line ...
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2answers
48 views

HackerRank Array left rotation using Swift

I solve this problem in Swift. Looking for feedback on my code or a better solution: ...
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1answer
51 views

Take two sets of randomly-sorted scores and find their common improvement percentage [on hold]

I was studying for an upcoming phone interview, and Googling programming terms which I needed to strengthen myself in. Well after I Googled "Dependency Injection", a banner appeared asking if I ...
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2answers
61 views

Evaluating a completely parenthesized arithmetic expression

I tried to solve the following problem in a programming challenge, but the verdict was time limit exceeded. Completely parenthesized expression Write a program that reads a completely ...
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0answers
17 views
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1answer
40 views

Swift Hackerrank Dynamic Array

I've solved this question. Wasn't sure if I was suppose to use a dictionary in this case, as the question was to use a dynamic array, but I didnt know how else to do it. Was wondering if I can get ...
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1answer
58 views

Swift Hackerrank 2D Array

I solved this question in Swift, but was wondering if there is a better way or if my code can be improved: Given a 6x6 2D Array: ...
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4answers
631 views

Find Watson's integer

Problem Statement: Watson gives Sherlock an array \$A_1\$, \$A_2\$ ... \$A_N\$. He asks him to find an integer \$M\$ between \$P\$ and \$Q\$ (both inclusive), such that, \$\min \{|A_i-M|, 1 \le i \...
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0answers
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Hackerrank - Quicksort 2 in Swift [closed]

I'm stuck on this problem. The whole code got ugly quickly, and the solution below did not work. Here is how I tried to solve quick sort: In the previous challenge, you wrote a partition method to ...
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3answers
86 views

How to decrease memory usage in codeeval Road Trip challenge

I'm solving easy CodeEval challenges in Python 2.7. Usually my solutions use around 256 bytes of memory according to CodeEval. With Road Trip however while time used is still low (30-40ms), memory is >...
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2answers
88 views

Clojure performance for solving Project Euler 72 (counting proper reduced fractions)

This is a solution of Project Euler 72 in Java. How may proper reduced fractions \$\dfrac{n}{d}\$ are there, where \$n < d \le 10^6\$? ...
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2answers
223 views

Converting Morse Code

Challenge Write a program which reads a file containing Morse Code and outputs the conversion. Specifications The first argument is a path to a file. The file contains multiple lines. Each line ...
6
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1answer
26 views

Counting single degree vertex removal rounds (from a graph)

Problem: In this problem I had to remove all vertices with degree one from a given graph in rounds and count how many rounds are required to remove all possible vertices with degree 1. e.g. ...
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1answer
83 views

I CAN HAS EULR 14, PLZ?

A few days ago I found myself learning lolcode. It turns out it's (almost) a real language and capable of handling (pseudo-)serious problems. So, let's try some (pseudo-)serious code this time. ...
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0answers
61 views

Determining position of point W.R.T to given line equation

Problem from hackerrank:: Problem Statement: There are N lines. Each line has an index between 1 and N. The slope of ...
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2answers
64 views

Finding the index of the character whose removal will make a palindrome

Before I get into describing by problem I'd like to point out I found this question under c++ tag. But the solution of that question is already implemented in my ...
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1answer
54 views

A Rule of Divisibility by 13

A Rule of Divisibility by 13 When you divide the successive powers of 10 by 13 you get the following remainders of the integer divisions: 1, 10, 9, 12, 3, 4. Then the whole pattern ...
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0answers
30 views

Greedy solution to minimize the max-min spread

I wrote this solution to contest challenge and I am new to D and was hoping for some tips to make it faster or more Dish. The challenge is to select K integers from a list of N integers (2 ≤ N ≤ 105, ...
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1answer
108 views

Project Euler #5 - Smallest multiple using Factor Table

This is a problem from Project Euler and on Hackerrank (here)- 2520 is the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder. What is the ...
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2answers
65 views

SPOJ ADDREV challenge - Adding reversed numbers

I'm a beginner Python (2.7) programmer, and I've just started solving basic problems on SPOJ. I correctly solved the ADDREV problem (http://www.spoj.com/problems/ADDREV/), however my code takes 0.06s ...
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1answer
165 views

“Parking” challenge solution

This is the problem statement. I have submitted successfully a \$O(n^2)\$ solution and I would like to know if there is a way to improve the running time to, maybe, \$O(n \log n)\$. Having dropped ...
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2answers
76 views

Project Euler #7: What is the 10,001st prime number?

By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13. What is the 10 001st prime number? How can I make this more efficient and cleaner? ...
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2answers
129 views

Pairwise programming challenge - Free code camp

Challenge: Given an array arr, find element pairs whose sum equal the second argument arg and return the sum of their indices. If multiple pairs, that have the ...
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2answers
630 views

Project Euler #5

2520 is the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder. What is the smallest positive number that is evenly divisible by all of the numbers from 1 ...
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6answers
736 views

Project Euler #4: Largest palindrome product

How can I make my code for Project Euler #4 more efficient and cleaner? Project Euler #4: Largest palindrome product: A palindromic number reads the same both ways. The largest palindrome made ...
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1answer
26 views

TLE on SPOJ for Prime Generator (PRIME1)

The objective is to find all primes between two given numbers. It is specified that the two numbers are \$\le\$ 1 billion and the difference between the two numbers is ~100,000. We are to repeat the ...
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2answers
147 views

HackerRank, Sherlock and Array

Here is the code I have written for a HackerRank challenge which takes multiple arrays, and attempts to determine if there exists an element in an array such that the sum of the elements on its left ...
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0answers
71 views

CodeEval - Lucky Tickets challenge

This a solution to the CodeEval's challenge "Lucky Tickets". After a failed attempt with brute-force calculations (no surprise here), I have tried to implement an algorithm that I found on ...
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2answers
71 views

SPOJ “It's a murder!” challenge

I wrote a solution for SPOJ "It's a murder!". I'm exceeding the time limit even after n log(n) solution and fast I/O. Given a list of numbers, I need to calculate the sum of the sum of the previously ...
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4answers
122 views

Remove adjacent duplicate characters

Introduction This problem is essentially equivalent to this HackerRank problem. The task is to remove all duplicate characters that are adjacent to each other in a given ...
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4answers
542 views

Project Euler 3: Largest prime factor

How can I improve my code, make it more efficient, and are there any tips you have? Project Euler 3: The prime factors of 13195 are 5, 7, 13 and 29. What is the largest prime factor of the ...
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2answers
148 views

HackerRank Sherlock and Squares: count perfect squares in an interval

I've exceeded the time limit on Sherlock and Squares on hackerrank.com. Problem Given the number of test cases and a range (inclusive), find the number of numbers within that range that are perfect ...
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3answers
113 views

Snakes on a prime

The challenge is to find and print the largest palindrome prime under 1000. ...
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4answers
978 views

Generalized Project Euler 1: A sledgehammer to crack a nut

The problem Project Euler 1 is one of the most asked questions on site. However I wanted to solve the more general problem of division. Multiples of a list If we list all the natural numbers ...
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1answer
111 views

C the sum of primes

The challenge is to calculate the sum of the first 1000 primes. The code applies a sieve thanks to past answer, here, and works but I wonder about the flexibility of this solution. ...
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3answers
662 views

Mars rover movement and position

I have written a solution of a Mars Rover problem in C++ using OOP, but I am not fully satisfied with the design. What changes can I make to improve the design? Problem description is: A rover’s ...
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6answers
184 views

Counting pairs of relatively prime numbers

Problem from Hacker Earth: Inverted GCD: Given an array a of \$N\$ numbers , you have to find the number of pair of indices \$i\$ and \$j\$ that satisfy the following relation: \$i &...
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4answers
182 views

Project Euler 4: Largest palindrome product

This solves Project Euler 4: Largest palindrome product using C# (specifically, using LINQPad). Any and all suggestions for improvements to either the C# code or the math/algorithm are very welcome. ...
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0answers
30 views

SPOJ GENERAL: sorting by swaps of distance k

I have been trying to solve this simple problem on SPOJ for quite some time now, but I keep on getting TLE (Time limit exceeded) for some reason. Since the problem is in Portuguese, a brief ...
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3answers
60 views

HackerRank “Nested Lists” Code

I completed the "Nested Lists" challenge on HackerRank, and would love any feedback on my code. My program is fed text with the number of students in a classroom, the name of a student, and their ...
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5answers
850 views

Largest Prime Factor (PE3) using OOP

I want to learn some C# syntax/paradigms (I'm more used to Java), and have been wanting to get a bit better at math as well, so I solved ProjectEuler3: Largest prime factor with the following small ...
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1answer
66 views

Calculating protein mass

This question is part of a series solving the Rosalind challenges. For the previous question in this series, see A sequence of mistakes. The repository with all my up-to-date solutions so far can be ...
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1answer
60 views

Scrabble tile-counting challenge

While reviewing this Scrabble Tile Counter, I decided to give it a try myself. Here is the challenge, from Reddit's /r/dailyprogrammer: Description For this challenge we will be using the ...
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1answer
47 views

Hamming distance in Scala

Problem Write a program that can calculate the Hamming difference between two DNA strands. GAGCCTACTAACGGGAT CATCGTAATGACGGCCT ^ ^ ^ ^ ^ ^^ Code ...
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1answer
98 views

Reading Input from file for sorting and rewriting

I am writing a program that reads a DAT file with names. The names are stored in an ArrayList of Type Name, the Name object can hold the first, middle and last name. Once the names are stored in the ...