Questions tagged [collatz-sequence]

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

55 questions
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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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“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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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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. ...
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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 ...
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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 ...
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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: <...
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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 (...
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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 ...
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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 (...
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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? ...
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Syracuse conjecture in OCaml

I am wondering how to optimize the following OCaml simple code. ...
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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 ...
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Generator for the collatz conjecture sequence

I tried to write this code as concisely as possible. Is this the best way to do it? ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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} \...
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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 ...
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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 ...
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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: ...
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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 ...
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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 ...
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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 ...
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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 ...
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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. ...
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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 ...
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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,...
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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 ...
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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 ...
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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 ...
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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. ...
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Project Euler: Longest Collatz Sequence

The Collatz Sequence is an iterative sequence that is defined for all positive integers as such: n → n/2 (n is even) n → 3n + 1 (n is odd) If 13 were to be entered into this sequence, the result ...
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Determine Collatz sequence length for given starting values

I am trying to get into the habit of solving programming puzzles in my spare time but am stuck on the first one (which I know can be for a large number of reasons, hence my posting for help). Shown ...
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Calculating the Collatz Conjecture

Today I read this thing about the Collatz Conjecture and wanted to try and write a program that calculates all the numbers. If you have any idea how the code could be shortened, please tell me. ...
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Project Euler #14 in Swift - Longest Collatz sequence

I just finished Project Euler #14 in Swift, and since there is not any version yet on Code Review, I would like to have some comments on what I did to try to improve it. The following iterative ...
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Euler Project 14 Longest Collatz Sequence [closed]

I have been working through the euler project and I have created the following code for Problem 14, which asks which starting number, under 1 million, produces the longest Collatz Sequence chain. It ...
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python : Collatz Sequence

I am a beginner in python. I found this problem in the book Automate the Boring Stuff with Python. How can I improve this program using latest version of python. ...
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Python script to calculate the Collatz conjecture

Here is the code. ...
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Python program for testing the Collatz Conjecture

This is a simple program to test if integers will follow an interesting, improvable statement that if disproven, calls for a bravo. But, ignoring the pretentious poetry, this code allows the user to ...