Tagged Questions
27
votes
7answers
4k views
Project Euler problem 1 in python
I'd like suggestions for optimizing this brute force solution to problem 1. The algorithm currently checks every integer between 3 and 1000. I'd like to cut as many unnecessary calls to ...
14
votes
6answers
2k views
Sherlock and The Beast
This is my solution to this question from Hackerrank.
Given N (<= 100000), find the largest N-digit number such that:
The number has only 3 and 5 as its digits.
Number of times 3 ...
11
votes
7answers
2k views
Is my solution to return kth row of the Pascal's triangle suitable for a job interview?
Question:
Given an index \$k\$, return the \$k\$th row of the Pascal's triangle.
For example, given \$k = 3\$, return \$[1,3,3,1]\$. Bonus points for using \$O(k)\$ space.
Can it be ...
10
votes
2answers
6k views
Problem 5 on Project Euler
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 ...
9
votes
3answers
198 views
How can I make my solution for Chef and Digits run faster?
Problem Statement
Given n digits and m indices x from 1 to n, calculate the
difference ...
9
votes
3answers
291 views
Optimizing “Herd Sums” problem using dynamic programming
I'm trying to solve a practice problem and all is well except for the last 2 inputs my solution is too slow. Just one loop is slowing it down I think.
Herd Sums
Execution Time Limit: 2 ...
7
votes
1answer
605 views
Project Euler 407: Is there any more optimal way to solve this idempotent equation (modulo n ring)?
Project Euler problem 407:
If we calculate a2 mod 6 for 0 ≤ a ≤ 5 we get: 0, 1, 4, 3, 4, 1.
The largest value of a such that a2 mod 6 = a is 4.
Let's call M(n) the largest value of a < n ...
7
votes
1answer
84 views
Project Euler Problem 33 - digit canceling fractions
Problem:
The fraction \$(\dfrac{49}{98})\$ is a curious fraction, as an inexperienced
mathematician in attempting to simplify it may incorrectly believe
that \$(\dfrac{49}{98}) = ...
7
votes
1answer
326 views
Solving systems of linear equations
I am working on the following problem (http://www.enigmagroup.org/missions/programming/9/).
You have a 6x6 table where the first 5 columns and rows are comprised of different types of shapes, 5 ...
6
votes
4answers
719 views
Finding the Pythagorean triplet that sums to 1000
Project Euler problem 9 says:
A Pythagorean triplet is a set of three natural numbers, a < b < c,
for which,
a2 + b2 = c2
For example, 32 + 42 = 9 + 16 = 25 = 52.
There ...
5
votes
2answers
523 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 ...
5
votes
1answer
462 views
Optimizing my code for Project Euler Problem #23 (Non-abundant sums)
Project Euler Problem 23 asks:
A perfect number is a number for which the sum of its proper divisors
is exactly equal to the number. For example, the sum of the proper
divisors of 28 would be ...
5
votes
3answers
819 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 ...
5
votes
3answers
77 views
Calculating the ranks of classmates' exam grades
The questions from hackerearth:
Geeko is in worry now because an exam is coming up and he has to know
what rank he can get on exams. So he goes back into the the school records
and finds the ...
5
votes
1answer
84 views
Project Euler 34 - digit factorials
145 is a curious number, as \$1! + 4! + 5! = 1 + 24 + 120 = 145\$.
Find the sum of all numbers which are equal to the sum of the
factorial of their digits.
Note: as \$1! = 1\$ and \$2! ...
4
votes
2answers
111 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 ...
4
votes
2answers
407 views
Euler 35 - python solution taking too long
Here is my solution for Project Euler 35. (Find the number of circular primes below 1,000,000. Circular meaning all rotations of the digits are prime, i.e. 197, ...
4
votes
2answers
289 views
k_diff challenge in Java
Puzzle Description
Given \$N\$ numbers, \$N <= 10^5\$, count the total pairs of numbers \$(N_i, N_j)\$ that have a difference of \$K = N_i - N_j\$ where \$0 < K < 10^9\$.
Input ...
4
votes
2answers
412 views
Project Euler problem 92 - square digit chains
Link to problem.
A number chain is created by continuously adding the square of the
digits in a number to form a new number until it has been seen before.
For example,
44 -> 32 -> 13 ...
4
votes
2answers
363 views
Project Euler #12 - highly divisible triangular number
The following is a solution to Project Euler problem number 12: which is to find the first triangular number with more than 500 divisors.
The code takes far too long to complete (over 10 minutes). Is ...
4
votes
1answer
295 views
Why is this divide and conquer algorithm inefficient?
I was solving one of the problem in USACO 2007 Open Silver:
Description
Farmer John has taken his cows on a trip to the city! As the sun sets, the cows gaze at the city horizon and observe ...
4
votes
2answers
93 views
Typeahead autocomplete functionality challenge
I'm working on a Talent Buddy challenge . In this challenge you have to design the autocomplete functionality of Twitter. You are given a list of queries and possible usernames. You have to return the ...
4
votes
1answer
415 views
Project Euler #14 (Longest Collatz Sequence) in Haskell
You can check the problem here:
http://projecteuler.net/problem=14
My first approach in Haskell was this:
...
4
votes
3answers
65 views
String self-similarity
It's a string problem I have been making on Hackerrank. It is executing fine on all test cases except the last two. These last two test case are declaring it "Terminated due to time out".
C programs ...
4
votes
1answer
706 views
Project Euler Problem 12 - Highly Divisible Triangular Number - Python Solution Optimization
Project Euler Problem 12 asks (paraphrased):
Considering triangular numbers Tn = 1 + 2 + 3 + … + n, what is the first Tn with over 500 divisors? (For example, T7 = 28 has six divisors: 1, 2, 4, ...
4
votes
2answers
284 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 ...
3
votes
2answers
757 views
Rot -n algorithm in Java
This is a rot-n (rotate n times) encrypt/decrypt algorithm, where n can be any integer (+/-).
It's written to encrypt/decrypt all the alphabets (upper/lower case) and leaving behind all non-alphas.
...
3
votes
2answers
121 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 ...
3
votes
2answers
301 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 ...
3
votes
1answer
162 views
Hackerrank Gem Stones
I am working on some problems on Hackerrank.
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 ...
3
votes
1answer
52 views
Truncatable Primes — Project Euler 37?
I just finished Project Euler 37 after a bit of debugging and can't figure out how to make it faster. Whenever I add extra tests that I want to speed the program up, it ends up just slowing it down. ...
3
votes
1answer
141 views
Truncating an integer from left to right and right to left
Project Euler problem 37 says:
The number 3797 has an interesting property. Being prime itself, it is possible to continuously remove digits from left to right, and remain prime at each stage: ...
2
votes
2answers
357 views
Project Euler, #4: Incorrect Results on 7-digit numbers
I've got my answer working (up until a 7-digit answer is requested, anyway), and would like some help
returning the correct answer
speeding up the results
I was thinking of storing the values of ...
2
votes
3answers
48 views
Speeding up Project Euler 43 - sub-string divisibility
The number, 1406357289, is a 0 to 9 pandigital number because it is
made up of each of the digits 0 to 9 in some order, but it also has a
rather interesting sub-string divisibility property.
...
2
votes
2answers
363 views
optimizing project euler #83 solution
Project Euler problem 83 asks:
In the 5 by 5 matrix below,
...
2
votes
7answers
2k views
Quadrant Queries challenge
Running the same test 10,000 times with cProfile tells me that most of the damage happens in the count() function. This is my attempt at a solution to the Quadrant Queries challenge from ...
2
votes
1answer
41 views
Performance of Codility MaxCounter challenge solution
I'm doing some of the Codility challenges using Ruby. The current challenge is "The MaxCounter," which is described as:
Calculate the values of counters after applying all alternating operations: ...
2
votes
1answer
53 views
Project Euler 39: Integer right triangles
I just finished Project Euler 39:
If p is the perimeter of a right angle triangle with integral length sides, {a, b, c} … For which value of p ≤ 1000, is the number of solutions maximised?
I'm ...
2
votes
1answer
130 views
Collecting magical berries
Here is the link of the problem for which I need your help.
I came up with solution and it is working fine for all cases, but it takes more time. I need your help in reducing the runtime of code. I ...
2
votes
1answer
44 views
Project Euler 40: Champernownes's Constant
I just finished Project Euler 40 with a brute force method. As usual, any optimizations would be helpful. (I feel like I'm getting better at this scripting thing)
...
2
votes
1answer
46 views
Project Euler 35 in Python
I'm back with a Python solution for Project Euler 35. Any help would be appreciated; I generate the numbers by observing that all circular primes can only have digits 1, 3, 7, and 9. Then I use the ...
2
votes
2answers
74 views
Optimizing Python code for Project Euler #5 (LCM of all numbers from 1 to 20)
This is my solution for the 5th problem of Project Euler, which asks for the least common multiples of the numbers from 1 to 20 (inclusive). Is there any way to improve the while loop conditional ...
2
votes
2answers
1k views
Project Euler #4 - Largest Palindrome Product
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 ...
2
votes
3answers
641 views
Is there any way to make my project Euler#14 solution faster?
I'm solving project euler problems and uploading my solutions to github.
Some of my solutions are just based on math and are thanks to that very fast, but #14 is way too slow, and I have no idea how ...
2
votes
2answers
1k views
HackerRank Algorithm Challenge 1: Insertion sort
This is my solution for HackerRank's first Algorithm Challenge, Insertion Sort Part 1. The challenge is to sort the array from least to greatest, the input being an array in sorted order, except for ...
2
votes
1answer
59 views
Typeahead Talent Buddy
Problem is Talent Buddy.
Your task is to
write a function that prints to the standard output (stdout) for each query the user name that matches the query
if there are multiple user names ...
1
vote
3answers
128 views
Optimize calculation of distances between pairs of points
I was trying to solve a challenge. The execution time should not exceed 5s, but for some value my code took longer. I want to know if I can optimize my code for performance.
...
1
vote
3answers
81 views
Optimizing Project Euler 36 - double-base palindromes
This one was quick and simple. Any optimizations?
...
1
vote
2answers
58 views
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.
...
1
vote
1answer
151 views
Better way of calculating Project Euler #2 (Fibonacci sequence)
Even Fibonacci numbers
Problem 2
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, ...
