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

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Project Euler #10 - summation of primes

(From Project Euler) The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17. Find the sum of all the primes below two million. Can someone please help me improve this code? ...
5
votes
3answers
139 views

Removing the largest values encountered so far in a list

The problem is, in summary: A set of values will be given. Whenever the input is -1, the largest number from the values inputted until then needs to be printed, and is then deleted. Here is the ...
5
votes
3answers
149 views

Caesar cipher exercise

I was doing this exercise from here. I made a solution work but can't help feel it could have been done in fewer lines. I'm quite new to python so I'm not too sure of the little shortcuts. ...
2
votes
1answer
60 views

Cutting stock recursion

This problem is identical to the one here: Suppose that you have been assigned the job of buying the plumbing pipes for a construction project. Your foreman gives you a list of the varying ...
10
votes
4answers
2k views

“Open and closed doors” riddle

Riddle Description: \$N\$ doors are closed. In the first pass, I open all of them. In the second pass, I toggle every second door. In the third pass, I toggle every third door. I continue this ...
16
votes
3answers
1k views

Diamond in the rough! Finding Gems in the rocks

Recently a question was asked that solved a hackerrank problem: Counting gems amongst the rocks The description of the challenge is: John has discovered various rocks. Each rock is composed of ...
2
votes
5answers
368 views

Counting the gems among the rocks

John has discovered various rocks. Each rock is composed of various elements, and each element is represented by a lowercase Latin letter from 'a' to 'z'. An element can be present multiple ...
2
votes
2answers
134 views

HackerRank “Manasa and Stones” in Python

Problem Statement: Manasa is out on a hike with friends. She finds a trail of stones with numbers on them. She starts following the trail and notices that two consecutive stones have a difference ...
5
votes
2answers
307 views

HackerRank “Service Lane” in Python

Problem statement: Calvin is driving his favorite vehicle on the 101 freeway. He notices that the check engine light of his vehicle is on, and he wants to service it immediately to avoid any ...
11
votes
4answers
1k views

Hackerrank “Sherlock Holmes” challenge

Watson gives to Sherlock an array: A1, A2, ⋯, AN. He also gives to Sherlock two other arrays: B1, B2, ⋯, BM and ...
4
votes
0answers
52 views

Project Euler #5 (Smallest multiple) in Swift

I found this one a little bit easier than the previous problems, but I was already familiar with the GCD/LCM formulas. ...
4
votes
3answers
202 views

Splitting an array in 2 parts such that one part sums to a multiple of 10 and other sums to an odd number

Given an array of ints, is it possible to divide the ints into two groups, so that the sum of one group is a multiple of 10, and the sum of the other group is odd. Every int must be in one ...
10
votes
2answers
611 views

Project Euler #4 (largest palindrome product) in Swift

A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99. Find the largest palindrome made from the product of two ...
6
votes
3answers
338 views

Clean Code attempt of HOLES problem on codechef.com

The problem asks you to take read an integer (number of words to read) and then process words entered counting the number of "HOLES" exist. Letters with HOLES are ...
2
votes
2answers
97 views

Project Euler 81 (minimum path sum through a matrix)

Problem Statement: In the 5 by 5 matrix below, 131 673 234 103 18 201 96 342 965 150 630 803 746 422 111 537 699 497 121 956 805 732 524 37 331 ...
7
votes
2answers
99 views

Project Euler #3 (Largest prime factor) in Swift

As mentioned in Project Euler #2 in Swift, I intend to work my way through Project Euler using Swift to make sure there aren't any tricks I'm missing. This is the problem statement for #3: The ...
11
votes
4answers
561 views

Project Euler #2 (Even Fibonacci numbers) in Swift

I figured working through Project Euler problems in Swift would be a good way to learn any tips or tricks. For example, tuples are something I'm not used to using, but they proved useful here. Using ...
-4
votes
2answers
72 views

“Magic Fraction” finder

A Magic Fraction for N is one that has the following properties: It is a proper fraction (the value is < 1) It cannot be reduced further (the GCD of the numerator and the denominator ...
7
votes
1answer
108 views

Optimizing “Poker hands” challenge solution

I'm trying to solve the project Euler problem 54. In the card game poker, a hand consists of five cards and are ranked, from lowest to highest, in the following way: High Card: Highest ...
5
votes
3answers
148 views

Project Euler #9 - Pythagorean triplets

This code works, and I'm trying to figure out if there's a better way to optimize it. As you can see, I've cut down drastically on time just by using numbers that work for ...
10
votes
3answers
598 views

Clean code attempt at ATM problem on codechef.com

The problem asks you to take an integer (debit amount) and a double (credit or initial balance amount) and process the requested debit verifying that 1 it's a multiple of the minimum denomimation ...
4
votes
1answer
79 views

Project Euler #12 very long runtime

Project Euler Problem 12 asks to find the value of the first triangular number to have over 500 divisors, where the \$n\$th triangular number is \$\sum_{i=1}^{n} i\$. The sequence of triangle ...
4
votes
2answers
118 views

Reverse Game HackerRank Ruby Solution

Problem Statement Akash and Akhil are playing a game. They have N balls numbered from 0 to N−1. Akhil asks Akash to reverse the position of the balls, i.e., to change the order ...
3
votes
4answers
129 views

Code Kata - Berlin Clock

To improve my programming style, I have been writing solutions for popular code katas. I have written a partial solution for the [Berlin Clock kata][1]. Can anyone critique the code and suggest ...
5
votes
2answers
114 views

Reducing the execution time of Online Community-Even Groups challenge

I have a coding problem for which I have attempted to solve with the below coding. However, my program is assessed as too slow in its execution and thus needs to be optimized to reduce the execution ...
-1
votes
1answer
2k views

Stone Game One Four [closed]

Alice and Bob are playing a game called "Stone Game". Stone game is a two-player game. Let N be the total number of stones. In each turn, a player can remove either one stone or four stones. The ...
9
votes
2answers
428 views

Clean code attempt on codechef.com FCTRL

I have been reading Clean Code and decided to start working problems on Codechef.com attempting to apply some of what I have learned. Do I seem to be on the right track or am I way off? The ...
8
votes
1answer
339 views

Project Euler #2

Problem: Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be: 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
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4answers
2k views

Project Euler #1

If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23. Find the sum of all the multiples of 3 or 5 below 1000. My ...
2
votes
3answers
106 views

“Remove Friends” problem time efficiency too slow

I'm doing this problem: After getting her PhD, Christie has become a celebrity at her university, and her Facebook profile is full of friend requests. Being the nice girl she is, Christie ...
19
votes
5answers
2k views

Aliens at the train

I solved this problem on SPOJ: The aliens have arrived to Earth and everything is in harmony, the two races can live together. However, one specific Female Alien does not want to see humans ...
6
votes
2answers
302 views

Project Euler #8: Maximum product of 13 consecutive digits

I've solved problem #8 in Project Euler, which asks to find the 13 consecutive digits with the greatest product from a particular 1000-digit number. I would like to hear any suggestions regarding my ...
3
votes
4answers
994 views

Given only a pointer to a node to be deleted in a singly linked list, how do you delete it?

Example: If a linkedlist list contains 10->20->30->40, and 2nd node has to be deleted then the output should be 10->30->40 This question is attributed to Geeksforgeeks. Looking for code-review, ...
4
votes
3answers
285 views

Google Code Jam - Store Credit

Below is my answer to the Google Code Jam's answer to the Store Credit. As usual the code run's perfectly well, however, my credit_pos function gives a warning when ...
5
votes
4answers
1k views

Google Code Jam - reverse words

As a sequel from my previous question, I decided to solve the next problem statement from the GCJ dash board. Any thorough critique, this time, with much attention to skill and technicalities would ...
4
votes
1answer
68 views

Log file processor - Programming Contest

Problem Description A profiler is a tool which provides information about run-time performance of an application. Lets say. you are given output file format of a profiler called Jensor. Jensor ...
11
votes
6answers
1k views

Google Code Jam - T9 Spelling with C++

I am trying to improve my coding skills. As a result, I solved the T9 Spelling question from the Google Code Jam dashboard. I will appreciate it if anyone could critique the code, and provide ...
3
votes
3answers
87 views

List primes within an interval

I'm trying to solve the SPOJ primes problem: Peter wants to generate some prime numbers for his cryptosystem. Help him! Your task is to generate all prime numbers between two given numbers! ...
1
vote
2answers
63 views

Calculating the Nth number in the supertable of two numbers

Below is the problem: Little Timmy is exceptionally good at math tables, so his teacher decided to make things a bit more interesting. His teacher gave him two numbers, A and B, and told him to ...
3
votes
3answers
465 views

Programming Challenge: Drawing Tool

Introduction to the problem You are free to implement any mechanism for feeding input into your solution. You should provide sufficient evidence with unit tests that your solution is ...
2
votes
3answers
401 views

Efficiency of Project Euler problem 35

The number, 197, is called a circular prime because all rotations of the digits: 197, 971, and 719, are themselves prime. There are thirteen such primes below 100: 2, 3, 5, 7, 11, 13, 17, 31, ...
2
votes
3answers
144 views

Finding Pythagorean Triple that sums to 1000

I am doing this Project Euler Question #9: A Pythagorean triplet is a set of three natural numbers, \$a < b < c\$, for which, $$a^2 + b^2 = c^2$$ For example, \$3^2 + 4^2 = 9 + 16 ...
2
votes
1answer
65 views

Efficiency on Project Euler Problem #8

I am doing Project Euler problem #8: The four adjacent digits in the 1000-digit number that have the greatest product are 9 × 9 × 8 × 9 = 5832. ...
4
votes
3answers
165 views

Sum of Squares/Square of Sum Difference

I am doing Project Euler problem #6. This is the question it asks: The sum of the squares of the first ten natural numbers is, $$1^2 + 2^2 + \ldots + 10^2 = 385$$ The square of the sum ...
10
votes
2answers
257 views

ISBN missing number solver

This is a programming contest question. Question as follows Problem Definition An ISBN (International Standard Book Number) is a ten digit code that uniquely identifies a book. The first 9 ...
2
votes
2answers
55 views

Efficiency of Project Euler 28 - number spiral diagonals

I have written a solution for Problem 28. Starting with the number 1 and moving to the right in a clockwise direction a 5 by 5 spiral is formed as follows: $$\begin{array}{rrrrr} ...
4
votes
4answers
520 views

Temperature conversion table

This is another solution for this challenge. Problem statement: In this challenge, write a program that takes in three arguments, a start temperature (in Celsius), an end temperature (in ...
10
votes
3answers
1k views

Wow that's a big integer! What's its largest prime factor?

I see that there are a few other people who have tackled Project Euler Problem #3. I hope you're not all sick of that question yet. I've not taken a look at those yet (purposely), but am about to now. ...
4
votes
1answer
69 views

Computation for finding the largest prime factor of 600851475143 is slow

I implemented the following for Project 3 in Project Euler: ...
9
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2answers
86 views

Contest code for a maze problem

I would like to ask your comments on my contest code for the following problem: We're going to have a slightly more logical puzzle today. We're going to write a program that will find a path through ...