Collatz conjecture: Difference between revisions
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#REDIRECT [[Hailstone sequence]] |
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{{draft task}} |
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'''Note: There is an ongoing discussion on removing this draft task in favour of [[Hofstadter-Conway $10,000 sequence|this one]]. Please [[Talk:Collatz conjecture#Retire this task?|give your opinion]], but DO NOT add to this page as it is likely to go away. ''' |
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<br>These programs calculate the [[wp:Collatz conjecture|Collatz sequence]] for a given integer, and stop if 1 is reached. |
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These programs were written before this task was created; as such, the specific actual requirements of this task have not yet been determined. |
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=={{header|bash}}== |
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<lang sh>collatz () |
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{ |
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n=$1; |
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echo $n; |
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if [ "$n" -gt 1 ]; then |
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#if odd |
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if [ "$(expr $n % 2)" -eq 1 ] ;then |
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collatz $(($n*3+1)) |
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else |
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collatz $(($n/2)) |
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fi |
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fi |
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}</lang> |
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=={{header|Befunge}}== |
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<lang befunge>&>:.:1-| |
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>3*^ @ |
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|%2: < |
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v>2/>+</lang> |
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=={{header|C}}== |
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<lang c>#include <stdio.h> |
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#include <stdlib.h> |
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int collatz( int n ) |
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{ |
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printf( "%i\n", n ); |
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if( n == 1 ) |
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return 1; |
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else |
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{ |
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if( (n % 2) == 0 ) |
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return collatz( n / 2 ); |
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else |
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return collatz(1 + (n * 3)); |
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} |
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return 1; |
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} |
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int main( int argc, char** argv ) |
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{ |
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int n = atoi( argv[1] ); |
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int i = collatz( n ); |
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printf( "%i\n", i ); |
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return 0; |
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}</lang> |
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=={{header|C++}}== |
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<lang cpp>#include <iostream> |
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using namespace std; |
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int main() { |
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int n; |
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cin >> n; |
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while (n > 1) { |
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if (n%2 != 0) { |
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n = n*3 + 1; |
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} else { |
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n = n/2; |
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} |
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cout << n << endl; |
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} |
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}</lang> |
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=={{header|Clojure}}== |
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<lang lisp>(defn collatz [n] |
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(println n) |
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(if (> n 1) (if (even? n) |
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(recur (/ n 2)) |
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(recur (inc (* 3 n)))))) |
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(collatz (read-string (read-line)))</lang> |
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=={{header|Common Lisp}}== |
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<lang lisp>(defun collatz (n) |
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(format t "~a~%" n) |
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(cond ((= n 1) 1) |
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((= (mod n 2) 0) (collatz (/ n 2))) |
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(t (collatz (+ 1 (* n 3)))))) |
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(collatz (read))</lang> |
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=={{header|Excel}}== |
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In cell '''A1''', place the starting number. |
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In cell '''A2''' enter this formula '''=IF(A1/2=ROUND(A1/2,0),A1/2,A1*3+1)''' |
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Drag and copy the formula down until 4, 2, 1 |
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=={{header|Ioke}}== |
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<lang ioke>collatz = method(n, |
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n println |
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unless(n <= 1, |
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if(n even?, collatz(n / 2), collatz(n * 3 + 1))) |
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)</lang> |
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=={{header|Java}}== |
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<lang java>public class Collatz { |
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public static void main(String[] args) { |
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for (int x = Integer.parseInt(args[0]); x > 1; x = (x % 2 == 0) ? x / 2 : x * 3 + 1) { |
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System.out.println(x); |
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} |
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} |
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}</lang> |
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=={{header|Fortran}}== |
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{{works with|Fortran|90}} |
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<lang fortran>program main |
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integer(4) :: n,i |
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write(6,*) "Input a natural number: " |
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read (6,*) n |
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do while(n.gt.1) |
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if(mod(n,2).eq.0) then ! number is even |
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n=n/2 |
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else ! number is odd |
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n=3*n +1 |
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endif |
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write(6,*) n |
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enddo |
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end program main</lang> |
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=={{header|Haskell}}== |
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<lang haskell>collatz :: Integer -> Integer |
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collatz n |
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| n == 1 = 1 |
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| even n = collatz (n `div` 2) |
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| otherwise = collatz (3 * n + 1)</lang> |
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=={{header|Oz}}== |
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<lang oz>declare |
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fun lazy {CollatzSeq N} |
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N > 0 = true %% assert |
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if N == 1 then [1] |
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elseif {IsEven N} then N|{CollatzSeq N div 2} |
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else N|{CollatzSeq 3*N+1} |
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end |
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end |
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in |
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{ForAll {CollatzSeq 42} Show}</lang> |
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=={{header|Perl}}== |
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<lang perl>#!/usr/bin/perl |
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die("Usage: $0 n\n") if (!$ARGV[0] || !int($ARGV[0])); |
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my $n = int($ARGV[0]); |
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while ($n > 1) { |
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$n = ($n % 2 != 0) ? $n * 3 + 1 : $n / 2; |
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print "$n\n"; |
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} |
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</lang> |
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=={{header|PHP}}== |
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<lang php>while($n > 1) |
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{ |
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if($n % 2 != 0) |
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{ |
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$n = $n*3 + 1; |
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} |
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else |
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{ |
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$n = $n/2; |
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} |
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echo $n . '<br/>'; |
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}</lang> |
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=={{header|PureBasic}}== |
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<lang PureBasic>While n>1 |
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If n%2 |
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n=(3*n)+1 |
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Else |
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n/2 |
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EndIf |
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PrintN(Str(n)) |
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Wend</lang> |
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=={{header|Python}}== |
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<lang python>def collatz(n): |
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while n > 1: |
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print (n) |
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if n%2==0: |
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n = n/2 |
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else: |
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n = (n*3)+1 |
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print (n)</lang> |
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=={{header|Scala}}== |
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<lang scala>def collatz(n:BigInt):Stream[BigInt] = |
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if (n == 1) { |
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Stream(1); |
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} else { |
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def next(n:BigInt):BigInt = if ((n % 2) == 0) (n / 2) else (n * 3 + 1); |
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Stream.cons(n, collatz(next(n))); |
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}</lang> |
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Latest revision as of 21:49, 13 November 2011
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