Comments on Collatz conjecture; Count the tries to reach $1$
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Collatz conjecture; Count the tries to reach $1$
Background
Check out this video on the Collatz conjecture, also known as A006577.
If you don't know what this is, we're given an equation of $3x + 1$, and it is applied this way:
- If $x$ is odd, then $3x + 1$.
- If $x$ is even, then $\frac{x}{2}$.
This will send us in a loop of 4 → 2 → 1 → 4 → 2 → 1...
, which got me into making this challenge.
Challenge
Write a program that establishes the Collatz conjecture:
- Take input of a positive integer. This will be the $x$ of the problem.
- Read the background for how it works, or watch the video for further explanation.
- The result should be how many turns it would take before reaching $1$. There, the sequence stops.
- This is code-golf, so the shortest program in each language wins!
Test Cases
From 1 to 10:
1 → 0 (1)
2 → 1 (2 → 1)
3 → 7 (3 → 10 → 5 → 16 → 8 → 4 → 2 → 1)
4 → 2 (4 → 2 → 1)
5 → 5 (5 → 16 → 8 → 4 → 2 → 1)
6 → 8 (6 → 3 → 10 → 5 → 16 → 8 → 4 → 2 → 1)
7 → 16 (7 → 22 → 11 → 34 → 17 → 52 → 26 → 13 → 40 → 20 → 10 → 5 → 16 → 8 → 4 → 2 → 1)
8 → 3 (8 → 4 → 2 → 1)
9 → 19 (9 → 28 → 14 → 7 → 22 → 11 → 34 → 17 → 52 → 26 → 13 → 40 → 20 → 10 → 5 → 16 → 8 → 4 → 2 → 1)
10 → 6 (10 → 5 → 16 → 8 → 4 → 2 → 1)
More of these can be found on OEIS. Thanks to @Shaggy for the link!
JavaScript, 28 bytes …
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[Sclipting], (UTF-16) 44 34 32 …
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[Python 3], 48 42 39 bytes …
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[Haskell], 43 39 bytes …
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Lua 5.4, 67 60 bytes ``` lu …
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[BQN], 31 28 bytes {1+( …
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Japt, 15 bytes É©Òß[U3Ä …
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J, 35 char ``` :@:&3)@.(2& …
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[Wolfram Language (Mathematica …
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C (gcc), 43 38 bytes ``` C …
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[AWK], 46 bytes {c=0;fo …
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Scala, 50 bytes ```scala Str …
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