# Questions tagged [programming-challenge]

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

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### Project Euler # 54 Poker hands in Python

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 value card. One Pair: Two cards of the same value. Two Pairs: ...
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### CtCI 16.8: Integer to English phrase in C++

I'm a C++ beginner working through Cracking the Coding Interview. This is question 16.8: Given any integer, print an English phrase that describes the integer (e.g., "One Thou­sand, Two Hundred ...
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### Project Euler # 56 Powerful digit sum in Python

A googol ($10^{100}$) is a massive number: one followed by one-hundred zeros; $100^{100}$ is almost unimaginably large: one followed by two-hundred zeros. Despite their size, the sum of the digits ...
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### Algorithm X implementation for Minimum Dominating Set

As as final project for a MOOC I wanted to write a program that finds the exact cover set/minimum dominating set from the given social network data. So I did end up with writing this. I kinda followed ...
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### Print sums of all subsets

Print sums of all subsets of a given set Problem summary : Print all subset sums of a given set of integers My approach is to store previous results and use them to calculate new (similar idea as ...
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### Project Euler # 53 Combinatoric selections in Python

There are exactly ten ways of selecting three from five, 12345: 123, 124, 125, 134, 135, 145, 234, 235, 245, and 345 In combinatorics, we use the notation, 5C3=10. In general, nCr = n! / r! (n−r)!, ...
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### Challenge - Construct binary tree from array [closed]

A coding challenge to construct a binary tree from an array. ...
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### Project Euler # 52 Permuted multiples in Python

It can be seen that the number, 125874, and its double, 251748, contain exactly the same digits, but in a different order. Find the smallest positive integer, x, such that 2x, 3x, 4x, 5x, and 6x, ...
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### Challenge: phone keypad to letters - return all possible strings

The challenge: Given a mapping of digits to letters (as in a phone number), and a digit string, return all possible letters the number could represent. You can assume each valid number in the ...
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### JavaScript Sort Stack Coding Challenge

A coding challenge to write a function sortStack that receives a stack of integers into ascending order (with largest integers on top) and returns another stack ...
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### Project Euler # 50 Consecutive prime sum in Python

The prime 41, can be written as the sum of six consecutive primes: 41 = 2 + 3 + 5 + 7 + 11 + 13 This is the longest sum of consecutive primes that adds to a prime below one-hundred. The longest sum ...
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### Project Euler # 49 Prime permutations in Python

The arithmetic sequence, 1487, 4817, 8147, in which each of the terms increases by 3330, is unusual in two ways: (i) each of the three terms are prime, and, (ii) each of the 4-digit numbers are ...
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### Project Euler # 48 Self powers in Python

The series, $1^1 + 2^2 + 3^3 + \ldots + 10^{10} = 10405071317$. Find the last ten digits of the series, $1^1 + 2^2 + 3^3 + \ldots + 1000^{1000}$. ...
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### Imperative and functional-programming solutions for Jumping on the Cloud challenge

Problem Statement Emma is playing a new mobile game that starts with consecutively numbered clouds. Some of the clouds are thunderheads and others are cumulus. She can jump on any cumulus cloud ...
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### Project Euler # 29: Distinct powers in Python

Consider all integer combinations of ab for 2 ≤ a ≤ 5 and 2 ≤ b ≤ 5: 2 ** 2 = 4, 2 ** 3 = 8, 2 ** 4 = 16, 2 ** 5 = 32 3 ** 2 = 9, 3 ** 3 = 27, 3 ** 4 = 81, 3 * 5 = 243 4 ** 2 = 16, 4 ** 3 = ...
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### Project Euler # 28: Number spiral diagonals in Python

Starting with the number 1 and moving to the right in a clockwise direction a 5 by 5 spiral is formed as follows: ...
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### Counting multiples of 3 up to a given number

I'm attempting a practice problem in Codeforces that requires you to find the number of multiples of 3 less than or equal to a given number. I have written the following code but it gives a TLE once ...
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### Project Euler # 25 The 1000 digit Fibonacci index

The Fibonacci sequence is defined by the recurrence relation: Fn = Fn−1 + Fn−2, where F1 = 1 and F2 = 1. Hence the first 12 terms will be: F1 = 1 F2 = 1 F3 = 2 F4 = 3 F5 = 5 ...
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### Project Euler # 24 Lexicographic permutations in Python

A permutation is an ordered arrangement of objects. For example, 3124 is one possible permutation of the digits 1, 2, 3 and 4. If all of the permutations are listed numerically or alphabetically, we ...
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### CodingBat: without_end

Link To Question Given a string, return a version without the first and last char, so "Hello" yields "ell". The string length will be at least 2. without_end('Hello') → 'ell' ...
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### Project Euler # 22 names scores in Python

Using names.txt (right click and 'Save Link/Target As...'), a 46K text file containing over five-thousand first names, begin by sorting it into alphabetical order. ...
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### Coding Challenge: Kattis

Short problem description: A sequence of numbers are antiarithemtic if there exists no three numbers a_i, a_j, ...
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### Project Euler # 21 amicable numbers Python

Let $d(n)$ be defined as the sum of proper divisors of $n$ (numbers less than $n$ which divide evenly into $n$). If $d(a) = b$ and $d(b) = a$, where $a ≠ b$, then $a$ and $b$ are an ...
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### Project Euler # 20 factorial digit sum in Python

n! means n × (n − 1) × ... × 3 × 2 × 1 For example, 10! = 10 × 9 × ... × 3 × 2 × 1 = 3628800, and the sum of the digits in the number 10! is 3 + 6 + 2 + 8 + 8 + 0 + 0 = 27. Find the sum of the ...
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### Project Euler # 19 Counting Sundays in Python

You are given the following information, but you may prefer to do some research for yourself. 1 Jan 1900 was a Monday. Thirty days has September, April, June and November. All the rest have ...
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### Letter case permutation

The question can be found here https://leetcode.com/problems/letter-case-permutation Given a string S, we can transform every letter individually to be lowercase or uppercase to create another ...
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### HarckerRank 2D Arrays Hourglass challenge

About this 2D Arrays HackerRank problem. The task is to find the maximum sum of a region in a 2D array. Specifically, it is to find the maximum sum of an "hourglass" region, defined as a 3x3 square ...
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### Adding a Node to the Linked List is taking a longer Time when using a reference to the Tail Node

I am trying to add two numbers in the form of linked List and return their result in a Linked List as given in https://leetcode.com/problems/add-two-numbers/ Question: You are given two non-empty ...
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### Staircase challenge - Python

Your task is to print all unique ways to climb a staircase of length n where, from each step, you can take steps of size x where ...
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### Project Euler #17: Number Letter Counts

If the numbers 1 to 5 are written out in words: one, two, three, four, five, then there are 3 + 3 + 5 + 4 + 4 = 19 letters used in total. If all the numbers from 1 to 1000 (one thousand) ...
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### Project Euler #14: Longest Collatz Sequence starting point

Problem statement: The following iterative sequence is defined for the set of positive integers: n → n/2 (n is even) n → 3n + 1 (n is odd) Using the rule above and starting with 13, we ...
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### Counting valleys traversed below sea level, given elevation changes

Problem Statement: Gary is an avid hiker. He tracks his hikes meticulously, paying close attention to small details like topography. During his last hike he took exactly steps. For every step ...
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### Project Euler, problem # 9, Pythagorean triplet

Project Euler #9, Pythagorean triplet is 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 = 25 = 5^...
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### Project Euler Problem # 8 maximum product of sequences

Is there any room for improvement? Your feedback would be helpful. Problem Statement: The four adjacent digits in the 1000-digit number that have the greatest product are 9 × 9 × 8 × 9 = 5832. Find ...
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### Project Euler problem # 3 is this the most efficient approach in Python or can I do better?

The problem statement: The prime factors of 13195 are 5, 7, 13 and 29. What is the largest prime factor of the number 600851475143 ? This code takes 9 seconds!, is there a better way? ...
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### HackerRank: Electronics Shop

Challenge from Hacker Rank - Monica wants to buy a keyboard and a USB drive from her favorite electronics store. The store has several models of each. Monica wants to spend as much as possible for ...
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### Bishop game - python

A bishop can capture any other bishop if it lies along the same diagonal line, so long as no other bishop is in its path. Given a list of coordinates of the bishops locations, and a board size, ...