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# Questions tagged [programming-challenge]

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

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### “Find the Min” challenge on Facebook Hacker Cup

I was solving the "Find the Min" problem on Facebook Hacker Cup. The code below works fine for the sample inputs given there, but for input size as big as 109, this takes hours to return the solution....
6k views

### SPOJ Problem 2 - Prime Generator

I'm trying to solve this problem. After a couple of tries, this is what I pulled off: ...
117 views

### Tips on projecteuler code optimization

I am working on projecteuler # 14, http://projecteuler.net/problem=14 and my code takes too long to run. Any tips, or hints for a beginner? Code: ...
648 views

### Mimicking T9 cell messaging

Today I solved a question from Google Code Jam: mimicking a cell phone keypad messaging. Here is the program, with goto statements. I know it is an unstructured ...
9k views

### Faster way to determine largest prime factor

Project Euler problem 3 asks: What is the largest prime factor of the number 600851475143? The first step I took is to determine the highest value number I should be looking at as a possibility (...
3k views

### Enormous Input Test - reducing program runtime

This is my solution to SPOJ Problem 442. How can I make this code run faster? What are some techniques that can be used to make this faster? I am getting a Time Limit Exceed Error here. ...
313 views

### Project Euler 10 - Summation of primes

I'm currently attempting to learn OCaml, and I'm working thought the Project Euler problems to do so. Here's some code I knocked together for problem 10. I am looking for idiomatic feedback rather ...
339 views

### Project Euler #35 in Common Lisp

To start with Common Lisp I am doing Project Euler using this language. Usually I manage to solve problems but I am quite sure that my code is not as efficient as it could be in Common Lisp. That is ...
1k views

### optimizing project euler #83 solution

Project Euler problem 83 asks: In the 5 by 5 matrix below, ...
1k views

### Golang solution to Project Euler #81 (min path through a matrix)

Project Euler problem 81 asks: In the 5 by 5 matrix below, ...
415 views

### Keeping Linq's readability (e.g. over goto statements) without sacrificing performance

I'm doing Project Euler problem 5 as a kata, focussing on TDD and code readability. The challenge is: What is the smallest positive number that is evenly divisible by all of the numbers from 1 to ...
3k views

### “The Trip” challenge from Programming Challenges [closed]

Here is a problem from the book Programming Challenges by Skiena and Revilla: The Trip A number of students are members of a club that travels annually to exotic locations. Their ...
807 views

### Google Code Jam - Alien Language

I've successfully solved the Alien Languages problem for Google Code Jam in Haskell: The algorithm is trivial - turn the patterns into regular expressions and see how many of the known words match ...
3k views

I more or less asked the same questions on stackoverflow.com, but maybe this is more for this forum. I have a hard time getting to grips with how to implement a top navigation (common for the whole ...
157 views

### Counting the ways to pick increasing sequences from sorted arrays

Preamble I am trying to learn JavaScript by writing code and looking up documentation, one problem at a time. I am already familiar with several "dynamic" languages, so I'm hoping to be productive ...
1k views

### Decoding binary string message

I am trying to learn some Java on my own, and I am tackling some "programming challenge" problems to practice the little I have learnt so far. Could anybody constructively critique this beginner's ...
1k views

### Array absurdity challenge

This is a CodeEval challenge taken from here: Challenge description: Imagine we have an immutable array of size N which we know to be filled with integers ranging from 0 to N-2, inclusive. ...
3k views

### Efficient implementation of a Dynamic Programming challenge

I wrote the following code for a Dynamic Programming problem but the online judge gives me a 'Time Limit Exceeded' error. How can I optimize this code to make it more efficient, especially the part ...
275 views

### Solving Project Euler problem #48 in Scala

I'm trying to learn some Scala and decided to try to tackle some Project Euler problems. For problem #48, coming from a Python background, my solution is the following one-liner: ...
431 views

### Project Euler #9 in haskell

I am trying to teach myself haskell by means of project Euler i sovled problem #9 by means of this code which is on the brute force side I was wondering if there is a more elegant/haskell/efficient ...
906 views

### Python Code Review - Project Euler #12

I just figured out Project Euler problem #12. This the first one I've done in Python, so I'm putting my code out there to hopefully get some constructive criticism. If anyone is interested, would ...
381 views

### Help me make my Python code clearer

Here's my solution to Project Euler problem 40. ...
298 views

### Devise an algorithm of complexity O(N) finding No of 1's from a 2 dimensional matrix[N][N] containing 1's and 0's

Assume a 2D [n][n] matrix of 1's and 0's. All the 1's in any row should come before 0's. The number of 1's in any row I should be at least the number of 1's row (i+1). Find a method and write a C ...
2k views

### Optimizing Code for Project Euler Problem 14

For Project Euler problem 14 I wrote code that runs for longer than a minute to give the answer. After I studied about memoization, I wrote this code which runs for nearly 10 seconds on Cpython and ...
3k views

### Finding the largest product of four consecutive numbers in a grid

Project Euler #11 asks to find the largest product of four numbers of a grid, where the four numbers occur consecutive to each other vertically, horizontally, or diagonally. Here is my solution in ...
843 views

### A little scheme programming challenge

I am learning scheme to get something new from a programming language and this code below is the solution to Project Euler question 21 but the code runs 10x slower than the listed Python code when I ...
289 views

### Isn't this dynamic programming?

I was solving problem 18 and 67 on Project Euler and came up with an algorithm that actually goes through almost all the possibilities to find the answer in O(n) time. However, ProjecEuler claims ...
1k views

### Median solving from Interview street in Python

Any suggestions to improve the performance of the following code? This code is exceeding the time limit for the last four cases. This is a solution to the problem https://www.interviewstreet.com/...
20k views

### Smallest Multiple

I just recently learned about Project Euler and have started doing the problems on there. I cleared problem 1 and 2, had no idea how to do 3 and 4, and started to do 5. I've seen the post regarding ...
222 views

### Spotify Best Before puzzle

I thought to spent my free time by solving a puzzle: Best Before Spotify Puzzle. I coded in Java, and yeah I did not clean up my code (just a rough work) and I have yet to optimize... so I did check ...
182 views

### How do I add memoization to this problem? [closed]

Problem Starting in the top left corner of a 22 grid, there are 6 routes (without backtracking) to the bottom right corner. How many routes are there through a 2020 grid? Solution Here is my ...
1k views

### Path sum - Dijkstra's algorithm in F#

I'm learning F# and I've decided to solve Project Euler's Problem #81 with Dijkstra's algorithm. In the 5 by 5 matrix below, the minimal path sum from the top left to the bottom right, by only ...
332 views

### Improving runtime of prime generation

I just answered the question on project euler about finding circular primes below 1 million using python. My solution is below. I was able to reduce the running time of the solution from 9 seconds to ...
279 views

### Euler 2 : Simple Fibonacci

I'm just starting to experiment with F# (from a C# background). I think I'm starting to get into the right way of thinking, but this code still seems pretty awkward. Is there a better (more terse) ...
988 views

### Shuttle Puzzle solver

How can I make this piece of code better? The problem to be solved is in the topmost comment. ...
2k views

### Connect graph from 2D array

I just completed Project Euler problem 18 which is a dynamic programming question through a graph of a triangle of numbers. The goal is to find the path from top to bottom of the triangle that has the ...
218 views

### Python vs. Java Runtime on Euler 22 - Name Scores

I want to know why Java is accepted over Python when it comes to runtime. On performing the following Euler problem, Python takes up less lines and runs faster (Python ~0.05s, Java ~0.3s on my machine)...
745 views

### “Recycled numbers” challenge

I wrote this program for the Google Code Jam problem, "Recycled numbers." It took around 2 and half minutes to solve the small input set on my dual core, 1GB RAM system. But for the large input set ...
232 views

### Product of all ints in array besides that an index i

I'm looking for a better implementation of the algorithm. ...
1k views

### ByteLandian challenge from CodeChef

I am trying to go through the problems on CodeChef and came across this problem: In Byteland they have a very strange monetary system. Each Bytelandian gold coin has an integer number written on ...
2k views

### More optimal “Making Change” Problem: Knapsack challenge

The problem description is: You are given n types of coin denominations of values v(1) < v(2) < ... < v(n) (all integers). Assume v(1) = 1, so you can always make change for any ...
2k views

### Canonical Python symmetric cryptography example

Python Cryptography Example Last weekend I wrote some code to help people use PyCrypto in a canonical fashion to symmetrically encrypt and decrypt strings and files. By canonical I mean I've followed ...
199 views

### Binary numbers challenge

I don't know if this is exactly refactoring but I recently completed a programming challenge to learn more about Ruby's iterators. However, I feel that the code is extremely "un-Ruby like". Would ...
2k views

### Finding minimum scalar product using ST Monad

Inspired by a Stack Overflow question, I decided to practice my Haskell by taking a crack at the Google Code Jam's Minimum Scalar Product problem: Given two vectors \\$\mathbf{v_1}=(x_1,x_2,\ldots,...
552 views

### Calculation of the distance to the next space station

I've made a solution for this problem: Task: Write a program for calculation of the distance to the next space station. Algorithm: First base is located at the distance equal to ...
262 views

### “Best before” puzzle

I'm new To C++ and decided to have a go at the Spotify challenges on their website. I have now finished but I get the feeling my code is just terrible. I'm guessing it would be very hard for someone ...