Questions tagged [collatz-sequence]

This tag should be used for code related to the sequences described in the Collatz conjecture.

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19
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1answer
325 views

Streaming Collatz

Challenge The recent question The 3n + 1 algorithm for a range inspired me to investigate a Java-8 dependent streaming mechanism for solving the programming challenge: For any two numbers ...
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Automate the Boring Stuff with Python - The Collatz sequence project

I am new to programming and started learning with Automate the Boring Stuff with Python. I just completed chapter 3's "Collatz sequence" project. I was wondering what would you do differently and ...
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2answers
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"Longest Collatz sequence" in C slower than in Python 3

This tight-looped memoization-less C solution to Project Euler's problem 14 seems efficient, but ran much slower than a similarly trivial Python 3 program. For the desired ...
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2answers
1k views
10
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4answers
5k views

Python Automate the Boring Stuff Collatz exercise

I'm looking for some feedback on my code for the collatz function exercise in the Python book Automate the Boring Stuff. It works, but doesn't feel very elegant to me. Is there a better way to ...
10
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3answers
4k views

3n + 1 problem optimization

The problem can be viewed here, since it's styled. I don't think I should just copy and paste. I implemented recessive function and dynamic programming to solve it. It can successfully passed UVa ...
10
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3answers
2k views

3n + 1 programming challenge in Python

I am trying to find a efficient solution for the 3n + 1 problem on uvaonlinejudge. The code I have uses memoization using a dictionary. I am getting a 'Time limit Exceeded' error when I submit the ...
10
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1answer
3k views

Project Euler #14 -- longest Collatz sequence

I was reading this question and realized that I didn't know Python well enough to critique the algorithm. So I wrote a Java solution instead, which is inappropriate for that question. Since there's ...
9
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1answer
575 views

Horridly Inefficient Project Euler #14 in Python - Collatz Sequences

I created this solution a while ago, and have been going back over my problems to try to make them all more efficient. I have been stuck on this one, and have tried a few different ideas. So far, my ...
8
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4answers
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Project Euler problem 14 (longest Collatz sequence) in Swift 3

I was trying to solve Project Euler:Problem 14 using Swift 3, but it takes ages to give me an answer, which is a sign that my code is absolute garbage performance-wise. What could I do to increase the ...
8
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3answers
7k views

Python - The Collatz Sequence

Can I get a review of my code for the the Collatz Sequence from Chapter three of Automate the Boring Stuff with Python? The Collatz Sequence Write a function named collatz() that has one ...
7
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3answers
21k views

Hailstone Sequences in Python

For the problem given: Douglas Hofstadter’s Pulitzer-prize-winning book, Gödel, Escher, Bach, poses the following mathematical puzzle. Pick a positive integer \$n\$ as the start. If \$n\$ is ...
7
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1answer
649 views

I CAN HAS EULR 14, PLZ?

A few days ago I found myself learning lolcode. It turns out it's (almost) a real language and capable of handling (pseudo-)serious problems. So, let's try some (pseudo-)serious code this time. ...
6
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2answers
368 views

Calculating numbers in the Collatz sequence

I have found two ways in which I can generate the Collatz sequence given a start number. I have looked briefly into their performance, but I'd like a more in depth/solid review into the difference in ...
6
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2answers
625 views

UVA 100: "The 3n + 1 problem"

I’ve solved UVA Problem 100: The 3n + 1 problem . In short, the task was to write a program that calculates a maximum of Collatz sequence lengths for any given range of starting values. My program: <...
6
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2answers
237 views

Basic Collatz program with input validation in Python

In chapter 3 of Automate the Boring Stuff with Python by Al Sweigart, one exercise asks to write a program which performs the Collatz sequence. I wrote a basic version first, then added and ...
6
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1answer
479 views

Locating the largest Collatz Sequence with memoization

Inspired by this question I wrote a memoized form of the collatz sequence calculator. The idea was to cache the sequence lengths for as many sequences as possible, from 0 to some value. I managed to (...
5
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4answers
5k views

Collatz Conjecture (c++)

I am new to C++ and this is my first program. The objective of this program is to fully complete the sequence called the Collatz conjecture. It concerns a sequence defined as follows: start with ...
5
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3answers
1k views

Optimize Collatz conjecture

This was the exercise: Exercise PSD Think about a number under 25. Write down the number. If the number is even, divide in to two en write down the result below. If the number isn’t even (...
5
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1answer
3k views

Finding maximum Collatz sequence between 1-1000000

I'm trying to find maximum the Collatz sequence between 1 and 1000000. I wrote the following code below. I guess it is correct but it is extremely slow. Can you give me a few hints to make it faster? ...
5
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1answer
316 views

Syracuse conjecture in OCaml

I am wondering how to optimize the following OCaml simple code. ...
5
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1answer
73 views

Hailstone Sequence in NASM

For practice, I wrote some NASM code that prints out the hailstone sequence of a (unfortunately, hardcoded) number. This is by far the most complex code I've ever written in NASM. I'd like advice on ...
5
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2answers
130 views

Project Euler Problem #277

I am trying to solve Euler project problem 277 using python 3.8. First, I will show my program and than ask specific questions for enhancements. The problem is a modified version of Collatz sequence. ...
5
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1answer
846 views

Hailstones and the Collatz Conjecture

The Collatz Conjecture is related to a type of problem called a Hailstone problem; because hailstones circulate up and down through a cloud around a planet until they eventually fall. The Collatz ...
5
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2answers
160 views

Euler Project 14 (Longest Collatz Sequence)

Project Euler 14 asks: Which starting number, under one million, produces the longest Collatz sequence? I've been trying to optimize this solution to execute in less then 1s. Agenda for first 50 ...
5
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1answer
108 views

Collatz Conjecture Disprover Unit - Googol Edition

The Wikipedia article about the Collatz Conjecture has these quotes: If the conjecture is false, it can only be because there is some starting number which gives rise to a sequence that does not ...
4
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3answers
1k views

Generator for the collatz conjecture sequence

I tried to write this code as concisely as possible. Is this the best way to do it? ...
4
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3answers
340 views

Calculating a Collatz Sequence

I've written a small script to calculate Collatz sequences. For background, read here about the Collatz conjecture. Largest number I've tried so far in my implementation is 93571393692802302 (which ...
4
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4answers
213 views

Optimized Longest Collatz Sequence

I'm writing a program to calculate the longest collatz sequence for positive integers below some N. I have optimized it as far as I can - is there anything more I could do to optimize it? Any ...
4
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2answers
896 views

Memoized Collatz sequence

Here is one of my programs that utilized memoization and array to improve performance and memory usage. The performance seems satisfactory but the memory usage is ridiculous and I can't figure out ...
4
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2answers
5k views

Project Euler #14 - Longest Collatz Sequence in Python

I recently solved Project Euler Problem 14 in Python: The following iterative sequence is defined for the set of positive integers: ...
4
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1answer
449 views

Computational verification of Collatz conjecture using OpenCL

This code review request follows my previous request Computational verification of Collatz conjecture. Unlike the previous program (which was designed for the CPU), this code should run on modern GPUs....
4
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1answer
2k views

Collatz Sequence in Python

I'm trying to use Python to solve the Project Euler problem regarding the Collatz sequence. With some research online, I have come up with the code below. However, it still takes a long time to find ...
4
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1answer
139 views

Generating the Collatz sequence in F#

Below is my code for building the collatz sequence so a given number. I'm trying to make the function tail recursive and I believe that this impelemtation is tail recursive but I'm not yet so ...
4
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0answers
213 views

Collatz fractal in Rust

Among the many fractals, there is Collatz Fractal based on a complex extension of: $$f(x) = \left\{ \begin{array}{ll} \frac{x}{2} \space \text{if even} \\ 3x + 1 \space \text{if odd} \end{array} \...
4
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0answers
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Project Euler #14 in Clojure (finding long Collatz sequence chain)

I'm working on a Clojure implementation for Project Euler #14, which asks for the initial element, under 106, that produces the longest collatz-sequence chain. I'm trying to make use of every ...
3
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4answers
957 views

Testing a Collatz Conjecture Conjecture (Python)

I had an intuition that the maximal trajectory lengths for collatz conjecture numbers would be produced by numbers of the form (2**n)-1 so I wrote a program to test ...
3
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2answers
96 views

Computational verification of Collatz conjecture using gmplib

Prerequisites The unsigned long type has a size of 64 bits. The following macros are defined. ...
3
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2answers
1k views

Calculating the Collatz conjecture of a number

I've made a Collatz Conjecture sequence calculator and I would like some feedback on what I can do better in regards to the code I've implemented, i.e. bad practices you see, improvements that can be ...
3
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2answers
515 views

Ulam numbers (calculates your life expectancy if you want to)

I'm new to Java and wanted to present to you my latest project: Ulam Numbers ...
3
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2answers
366 views

Contest Solution: Hailstones

The Problem In the January 1984 issue of Scientific American, an interesting sequence of numbers known as a hailstone series was described. The series is formed by generating the next number ...
3
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2answers
401 views

Counting terms in Collatz sequences until 1 is reached or a limit is exceeded

My friend and I are into competitive programming and we wrote two very similar programs for a problem. His got accepted with a runtime of 0.6 s while mine didn't get accepted even after 3 s. I was ...
3
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3answers
585 views

Longest Collatz sequence using dynamic programming in Java

I'm not getting where else should I optimize it. Is there any way to optimize this code any further? Just give me hints. ...
3
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2answers
157 views

UVA 100: “The 3n + 1 problem” take 2

This is my second attempt to solve this problem, my first attempt is here: UVA 100: "The 3n + 1 problem" This time I tried to take lessons from the failures and mistakes You pointed out in ...
3
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1answer
710 views

Project Euler #14 (Longest Collatz sequence)

A Collatz sequence for a given positive integer \$n\$ is to take half of \$n\$ if even and \$3n+1\$ if \$n\$ is odd; repeat until the value goes to \$1\$. The question is which number from 1 to 1,000,...
3
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1answer
336 views

Computational verification of Collatz conjecture

Prerequisites The typedef name uint128_t designates an unsigned integer type with width exactly 128 bits. The ...
3
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1answer
328 views

Collatz Conjecture Meet of 2 Numbers

I need the most efficient way to calculate when the Collatz Conjecture of two numbers, a and b respectively, are the same. Here ...
3
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2answers
533 views

Efficient solution to Project Euler 14 (Longest Collatz sequence)

This is an iterative review. I asked for reviews on a Collatz sequence generator here. I tried to address all of the suggestions that were made. I've added a new function ...
3
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4answers
2k views

Find out the number under 1 million which produces the largest Collatz Sequence

So, I have written a code which calculates the number under n( 1 million in this case) which produces the largest Collatz Sequence in that ...
3
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1answer
137 views

Project Euler problem #14 (longest Collatz chain) in Swift

This is my Swift code for finding the starting number, under one million, which produces the longest collatz chain. ...