Sorting algorithms/Bubble sort: Difference between revisions
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==[[Forth]]== |
==[[Forth]]== |
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[[Category:Forth]] |
[[Category:Forth]] |
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Sorts the 'cnt' cells stored at 'addr'. Uses forth local variables for clarity. |
Sorts the 'cnt' cells stored at 'addr' using the test stored in the deferred word 'bubble-test'. Uses forth local variables for clarity. |
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defer bubble-test |
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' > is bubble-test |
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: bubble { addr cnt -- } |
: bubble { addr cnt -- } |
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cnt 1 |
cnt 1 do |
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addr cnt i - cells bounds |
addr cnt i - cells bounds do |
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i 2@ |
i 2@ bubble-test if i 2@ swap i 2! then |
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cell + |
cell +loop |
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loop ; |
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This is the same algorithm done without the local variables: |
This is the same algorithm done without the local variables: |
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: bubble ( addr cnt -- ) |
: bubble ( addr cnt -- ) |
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dup 1 |
dup 1 do |
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2dup i - cells bounds |
2dup i - cells bounds do |
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i 2@ |
i 2@ bubble-test if i 2@ swap i 2! then |
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cell + |
cell +loop |
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loop ; |
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Test either version with this: |
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create test |
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8 , 1 , 4 , 2 , 10 , 3 , 7 , 9 , 6 , 5 , |
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here test - cell / constant tcnt |
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test tcnt cells dump |
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' > is bubble-test |
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test tcnt bubble |
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test tcnt cells dump |
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' < is bubble-test |
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test tcnt bubble |
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test tcnt cells dump |
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==[[Haskell]]== |
==[[Haskell]]== |
Revision as of 21:18, 2 February 2007
You are encouraged to solve this task according to the task description, using any language you may know.
Sorting Algorithm
This is a sorting algorithm. It may be applied to a set of data in order to sort it.
For comparing various sorts, see compare sorts.
For other sorting algorithms, see sorting algorithms, or:
Heap sort | Merge sort | Patience sort | Quick sort
O(n log2n) sorts
Shell Sort
O(n2) sorts
Bubble sort |
Cocktail sort |
Cocktail sort with shifting bounds |
Comb sort |
Cycle sort |
Gnome sort |
Insertion sort |
Selection sort |
Strand sort
other sorts
Bead sort |
Bogo sort |
Common sorted list |
Composite structures sort |
Custom comparator sort |
Counting sort |
Disjoint sublist sort |
External sort |
Jort sort |
Lexicographical sort |
Natural sorting |
Order by pair comparisons |
Order disjoint list items |
Order two numerical lists |
Object identifier (OID) sort |
Pancake sort |
Quickselect |
Permutation sort |
Radix sort |
Ranking methods |
Remove duplicate elements |
Sleep sort |
Stooge sort |
[Sort letters of a string] |
Three variable sort |
Topological sort |
Tree sort
In this task, the goal is to sort an array of elements using the bubble sort algorithm. The elements must have a total order and the index of the array can be of any discrete type. For languages where this is not possible, sort an array of integers.
Algorithm
The bubble sort is generally considered to be the simplest sorting algorithm. Because of its simplicity and ease of visualization, it is often taught in introductory computer science courses. Because of its abysmal performance, it is never used anywhere else.
The bubble sort works by passing sequentially over a list, comparing each value to the one immediately after it. If the first value is greater than the second, their positions are switched. Over a number of passes, at most equal to the number of elements in the list, all of the values drift into their correct positions. (Large values "bubble" rapidly toward the end, pushing others down around them.) A boolean variable is used to track whether any changes have been made in the current pass; when a pass completes without changing anything, the algorithm exits.
This can be expressed in pseudocode as follows (assuming 1-based indexing):
repeat forever set hasChanged to false repeat with index from 1 to (itemCount - 1) if (item at index) > (item at (index + 1)) swap (item at index) with (item at (index + 1)) set hasChanged to true if hasChanged is false exit
Examples
Ada
Compiler: GCC 4.1.2
generic type Element is private; with function "=" (E1, E2 : Element) return Boolean is <>; with function "<" (E1, E2 : Element) return Boolean is <>; type Index is (<>); type Arr is array (Index range <>) of Element; procedure Bubble_Sort (A : in out Arr); procedure Bubble_Sort (A : in out Arr) is Finished : Boolean; Temp : Element; begin loop Finished := True; for J in A'First .. Index'Pred (A'Last) loop if A (Index'Succ (J)) < A (J) then Finished := False; Temp := A (Index'Succ (J)); A (Index'Succ (J)) := A (J); A (J) := Temp; end if; end loop; exit when Finished; end loop; end Bubble_Sort; -- Example of usage: with Ada.Text_IO; use Ada.Text_IO; with Bubble_Sort; procedure Main is type Arr is array (Positive range <>) of Integer; procedure Sort is new Bubble_Sort (Element => Integer, Index => Positive, Arr => Arr); A : Arr := (1, 3, 256, 0, 3, 4, -1); begin Sort (A); for J in A'Range loop Put (Integer'Image (A (J))); end loop; New_Line; end Main;
C++
Compiler: g++ 4.0.2
#include <iostream> #include <algorithm> template< typename ARRAY_TYPE, typename INDEX_TYPE > void bubble_sort( ARRAY_TYPE array[], INDEX_TYPE size ) { bool done = false ; while( !done ) { done = true ; for( INDEX_TYPE i = 0 ; i < size - 1 ; i++ ) { if( array[i] > array[i+1] ) { done = false ; ARRAY_TYPE temp = array[i+1] ; array[i+1] = array[i] ; array[i] = temp ; } } } } template< typename TYPE > void print( TYPE val ) { std::cout << val << " " ; } int main( int argc, char* argv[] ) { int array[] = { 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 } ; bubble_sort( array, 10 ) ; std::for_each( &array[0], &array[10], print<int> ) ; std::cout << std::endl ; //But in real life... int data[] = { 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 } ; std::sort( data, data+10 ) ; std::for_each( data, data+10, print<int> ) ; std::cout << std::endl ; }
Forth
Sorts the 'cnt' cells stored at 'addr' using the test stored in the deferred word 'bubble-test'. Uses forth local variables for clarity.
defer bubble-test ' > is bubble-test : bubble { addr cnt -- } cnt 1 do addr cnt i - cells bounds do i 2@ bubble-test if i 2@ swap i 2! then cell +loop loop ;
This is the same algorithm done without the local variables:
: bubble ( addr cnt -- ) dup 1 do 2dup i - cells bounds do i 2@ bubble-test if i 2@ swap i 2! then cell +loop loop ;
Test either version with this:
create test 8 , 1 , 4 , 2 , 10 , 3 , 7 , 9 , 6 , 5 , here test - cell / constant tcnt test tcnt cells dump ' > is bubble-test test tcnt bubble test tcnt cells dump ' < is bubble-test test tcnt bubble test tcnt cells dump
Haskell
This version checks for changes in a separate step for simplicity, because Haskell has no variables to track them with.
bsort :: Ord a => [a] -> [a] bsort s = case _bsort s of t | t == s -> t | otherwise -> bsort t where _bsort (x:x2:xs) | x > x2 = x2:(_bsort (x:xs)) | otherwise = x:(_bsort (x2:xs)) _bsort s = s
This version uses the polymorphic Maybe type to designate unchanged lists. (The type signature of _bsort is now Ord a => [a] -> Maybe [a].) It is slightly faster than the previous one.
bsort :: Ord a => [a] -> [a] bsort s = case _bsort s of Nothing -> s Just s2 -> bsort s2 where _bsort (x:x2:xs) | x > x2 = case _bsort (x:xs) of Nothing -> Just $ x2:x:xs Just xs2 -> Just $ x2:xs2 | otherwise = case _bsort (x2:xs) of Nothing -> Nothing Just xs2 -> Just $ x:xs2 _bsort _ = Nothing
Perl
Interpreter: perl 5.8.8
# Sorts an array in place and returns a copy sub bubble_sort (@) { my $len = @_ - 1; for my $i (0..$len-1){ for my $j ($i+1..$len){ @_[$i,$j] = @_[$j,$i] if $_[$j] lt $_[$i]; } } return @_; }
# Usage @a = qw/G F C A B E D/; bubble_sort(@a);
Alternate "Long Hand" Perl Method
sub Bubble_Sort { my @list = @_; my $temp = 0; my $done = 0; my $elements = $#list + 1; while ($done == 0) { $done = 1; for (my $i=0;$i<$elements;$i++) { if ($list[$i] > $list[$i+1] && ($i + 1) < $elements) { $done = 0; $temp = $list[$i]; $list[$i] = $list[$i+1]; $list[$i+1] = $temp; } } } return @list; }
#usage my @test = (1, 3, 256, 0, 3, 4, -1); print join(",",Bubble_Sort(@test));
Python
def bubblesort(seq): for i in xrange(1, len(seq)): for j in range(len(seq) - i): if seq[j] > seq[j+1]: seq[j], seq[j+1] = seq[j+1], seq[j] data = [3, 78, 4, 23, 6, 8, 6] bubblesort(data) print data # [3, 4, 6, 6, 8, 23, 78]
Ruby
Although the native Ruby sort method for Arrays if much faster (O(n*log(n)) versus O(n**2)), you can find a Ruby version of Bubble sort hereunder. It adds the bubblesort! method to the Array object. Below are two different methods that show four different iterating constructs in ruby.
class Array def bubblesort1! length.times do |j| for i in 1...(length - j) if self[i] < self[i - 1] self[i], self[i - 1] = self[i - 1], self[i] end end end return self end
def bubblesort2! each_index do |index| (length - 1).downto( index ) do |i| a, b = self[i-1], self[i] a, b = b, a if b < a end end return self end end
puts [3, 78, 4, 23, 6, 8, 6].bubblesort1! # => [3, 4, 6, 6, 8, 23, 78]