# Questions tagged [programming-challenge]

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

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### Any way to optimize this already fast Python solution to Project Euler 31 (coin sums)?

This is a Python solution for all general cases. Any suggestions at all would be appreciated; in my opinion it's already quite good! Here's a link to the problem. ...
2k views

### Project Euler 30 — Digit fifth powers

Here's my solution for Project Euler Problem 30. Any optimizations in time, space, or style would be greatly appreciated. ...
294 views

### Project Euler 29

Here's a link to the problem. Is there any way I could optimize/speed up this code, perhaps make it more Pythonic? ...
457 views

### Make Project Euler 27 solution idiomatic Ruby

I learned to program in Java and C# and in my free time I am using Ruby because it is fun. Unfortunately I have the feeling that I write Ruby code like I am making Java or C# code. I have learned to ...
810 views

### String pattern riddle

I've tried this problem on Codeforces. Given a set of string patterns, all of which are the same length, and which consist of literal lowercase ASCII characters and ...
25k views

### Perm-Missing-Elem: 100% functional score, but only 60% performance

I cannot figure out why I didn't get 100% success from the Codility's Perm-Missing-Element test even I solve with $O(n)$. I will appreciate any advice/answers. You can see the problem, my code, and ...
2k views

### Project Euler Problem 11: Largest product in a grid

Here is my implementation to project Euler Problem 11. I did this problem a bit later, when I learned how to input from a txt file. The problem context can be seen here. I did add "\n" to the end of ...
4k views

### Hackerrank - Sherlock and the Beast

I am trying to solve the Sherlock and The Beast HackerRank challenge. Most tests timeout, however when I try a custom stretch test case (T = 20 and all N = 100000), it returns successfully, so I'm not ...
1k views

### Project Euler 18/67: Maximum Sum from Top to Bottom of the Triangle

This is my attempt at Project 18/67 of Project Euler. You can see the problem information, and obtain the needed txt file from here. I had some help with the split function, and help on how to use an ...
3k views

### Project Euler 14: Longest Collatz Sequence

I've brute forced solve Project Euler 14. This is my first attempt at trying to solve it, by caching already solved answers, and skipping them as I run it, I am finding the program take's almost twice ...
2k views

### Project Euler 28 - Number Spiral Diagonals

Project Euler 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} \color{red}{21} &22 &...
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### Project Euler 27 - Quadratic Primes

Project Euler problem 27 I decided to try simple brute force, and it worked surprisingly quickly. How can this be optimized? ...
234 views

### Eight Directions Crossword

I solved a problem which you can read about here, but it gives me "time limit exceeded" even though it runs in 4 seconds. I really don't understand why. I don't think my code can be any simpler, ...
127 views

### Counting matrices

I need help optimizing my code to run faster (it works but I get Time Limit Exceeded) for this problem. (Don't pay attention to readInt() function, its only used ...
4k views

### Project Euler #3 - largest prime factor

I was going through the Project Euler problem #3 and made a program to solve it. The problem is as follows: The prime factors of 13195 are 5, 7, 13 and 29. What is the largest prime factor of the ...
2k views

### Recursive uniform cost search that needs to be optimized

I have this uniform cost search that I created to solve Project Euler Questions 18 and 67. It takes the numbers in the txt file, places them into a two dimensional list, and then traverses them in a ...
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### Rendition of Project Euler 26 - reciprocal cycles

This is my solution for problem 26 from Project Euler: ...
26k views

### Codility Frog Jump - Count minimal number of jumps from position X to Y

Here is a question I tried from the Codility train website: A small frog wants to get to the other side of the road. The frog is currently located at position X and wants to get to a position ...
329 views

### “Chef and Digits” Java solution

I am looking for a review on the following code which is for this question. I am looking for a general review of the code. I am specifically also looking for advice on how to make this code run more ...
501 views

### Chef and Digits

I am looking for a review on the following code which is for this question. I am looking for a general review of the code. I am specifically also looking for advice on how to make this code run more ...
103 views

### Calculate difference of indices

The challenge is to reconstruct an n-digit number using the following information: On each step, you choose an index x from 1 to n. For all indices y (y < x), you calculate the difference by =...
616 views

### Project Euler 1 (sum of multiples of 3 or 5 under 1000)

I solved this a while ago. In the moment I solved it I was learning Scheme and, well, I still am. I'm not looking at the best solution (I searched for it and coded it already, in Python), what I want ...
431 views

### How can I make my solution for Chef and Digits run faster?

Problem Statement Given $n$ digits and $m$ indices $x$ from $1. \ldots,n$, calculate the difference $b_y = a_x - a_y$ for all indices $y \; (y < x)$. Then, calculate $B1$, the ...
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### Prime generator program SPOJ time limit exceed

Problem Statement Input The input begins with the number t of test cases in a single line (t<=10). In each of the next t lines there are two numbers m and n (1 <= m <= n <= ...
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### Count distinct primes, discarding palindromes, in under 2 seconds

Problem Statement Generate as many distinct primes P such that reverse (P) is also prime and is not equal to P. Output: Print per line one integer( ≤ 1015 ). Don't print more than 106 ...
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### Binary tree level order traversal algoritm

I am trying to solve this Binary tree lever order traversal: ...
476 views

### Increasing readability of maximum path sum algorithm

I had written a solution for Project Euler problem 18 in Python 3. It is good in its efficiency but the problem is the readability and I think reuse. The algorithm used is that at every iteration ...
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### Genomic Range Query

Recently I worked on one of the Codility Training - Genomic Range Query (please refer to one of the evaluation report for the detail of this training). The proper approach for this question is using ...
2k views

### Project Euler #22 - Name scores

I have written code in C++ 11 and check output with Project Euler site, and it is correct. I am not showing output, just to keep it secret, at least from my end. Please review my C++ 11 code. ...
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### Project Euler #4 - Largest Palindrome Product

Problem Statement: 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 ...
781 views

### 'Team Split' problem

Below is my solution for this 'Team Split' problem. In summary, the problem is to find relative strength of 2 teams by finding the difference between their total strength (individual strengths can be ...
699 views

### Ten thousand and first prime checker takes a very long time

I am attempting problem 7 on Project Euler. I have come up with this solution which works fine for finding smaller nth prime numbers, but really lags when it comes to higher nth prime numbers. I am ...
874 views

### Simple framework for Google Code Jam problems

My main concern is code style. Could you review this? ...
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### Tape Equilibrium

I picked the first test (Tape Equilibrium) from Codility here. Question: A non-empty zero-indexed array A consisting of N integers is given. Array A represents numbers on a tape. Any integer P, ...
378 views

### Speeding up my implementation of Project Euler #3

Project Euler problem 3 asks for the largest prime factor of 600851475143. I have gone from 96 lines to 17 lines taking hits at this one. This is what I am left with after all of that effort: ...
2k views

### Lychrel calculator (Project Euler 55)

If we take 47, reverse and add, 47 + 74 = 121, which is palindromic. Not all numbers produce palindromes so quickly. For example, ...
591 views

Please let me know what you think. Is the code well written? Am I using best practices (like when I chose === over ==)? Is my ...
6k views

### Sherlock and The Beast

I have recently written the program for the Sherlock and The Beast' HackerRank challenge. That's working fine, but the problem is that it takes too much time if a big number is given as a input. I ...
725 views

### Level-traverse a binary tree

Level traverse binary tree question: Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level). For example: Given binary tree ...
2k views

### Project Euler “Largest product in a grid” (#11) in Java 8

I have come up with a Java 8 solution for the following problem: In the 20×20 grid below, four numbers along a diagonal line have been marked in red (bold here). 08 02 22 97 38 15 00 40 00 75 ...
865 views

### Project Euler “Largest prime factor” (#3) in Java

The prime factors of 13195 are 5, 7, 13 and 29. What is the largest prime factor of the number 600851475143 ? I wrote the following code with help of some Java 8, I'll explain the equivalent to ...
3k views

### Project Euler “Even Fibonacci numbers” in Java 8

I'm looking for general advice on my code on the following 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 ...
564 views

### Finding the next higher digital permutation of a number

This is my solution for CodeEval challenge 44. You are writing out a list of numbers.Your list contains all numbers with exactly Di digits in its decimal representation which are equal to i, for ...
204 views

### Exercism assignment for word-count in Clojure

I would appreciate some insights / comments from Clojure regulars out there about my submission here. ...
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### Exercism assignment word-count in Python

Can someone review my code which I put on exercism.io for the word-count exercise (found here)? ...
207 views

### Project Euler #15 in haskell

I've solved Project Euler #15 in Haskell, but I feel like there might be a better way to express my solution that I'm not seeing. I start out defining my types: ...