411 REFERENCE · Wikibooks
Algorithm Implementation/Sorting/Gnome sort
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
Gnome sort
C
void gnome_sort(int *array, int size){
int i, tmp;
for(i=1; i<size; ){
if(array[i-1] <= array[i])
++i;
else{
tmp = array[i];
array[i] = array[i-1];
array[i-1] = tmp;
--i;
if(i == 0)
i = 1;
}
}
}
C++
#include <algorithm> // for std::swap
void gnomeSort( int *array, int size )
{
for ( int i = 1; i < size; ) {
if ( array[i-1] <= array[i] ) {
++i;
}
else {
std::swap( array[i-1], array[i] );
--i;
if ( i == 0 ) {
i = 1;
}
}
}
}
C++ using bidirectional iterators
#include <algorithm> // for std::iter_swap
template <typename Iterator>
void gnome_sort(Iterator begin, Iterator end)
{
Iterator current = begin;
Iterator before_current;
while (current != end)
{
if (current == begin || *before_current <= *current)
{
++current;
}
else
{
std::iter_swap(before_current, current);
--current;
}
before_current = current;
--before_current;
}
}
Optimized C++ using iterators
#include <algorithm> // for std::iter_swap
#include <iterator> // for std::advance
template <typename Iterator>
void gnome_sort(Iterator begin, Iterator end)
{
Iterator current = begin;
Iterator before_current;
size_t step = 1;
while (current != end)
{
if (current == begin || *before_current <= *current)
{
std::advance(current, step); // possible leap optimization
step = 1;
}
else
{
std::iter_swap(before_current, current);
--current;
++step;
}
before_current = current;
--before_current;
}
}
The optimized version makes the "gnome" (represented by the 'current' iterator here) leap back to the right i.e. to the place where it needed to swap the flower pots on its farthest reached position so far. This also avoids redundant comparisons. On average the optimization results in cutting the time by one/third on a modern x86 machine. (A wise gnome sort? :). However, the optimization works best if the iterators are random access iterators. Otherwise the algorithm works almost like the non-optimized version - it still avoids redundant comparisons though.
C#
void GnomeSort( int[] array )
{
for ( int i = 1, temp_value; i < array.Length; )
{
if ( array[i-1] <= array[i] )
i += 1;
else
{
temp_value = array[i-1];
array[i-1] = array[i];
array[i] = temp_value;
i -= 1;
if ( i == 0 )
i = 1;
}
}
}
Rust
This is the optimized version of Gnome Sort with the jump/leap optimization coded in Rust.
fn skipping_gnome_sort(arr: &mut Vec<i32>)
{
let mut i: usize = 0;
let mut n: usize = arr.len();
let mut prev: usize = 0;
while i < n
{
if i == 0 || arr[i] >= arr[i - 1]
{
if prev != 0 { i += prev; prev = 0; }
i += 1;
}
else
{
arr.swap(i, i - 1);
prev += 1;
i -= 1;
}
}
}
FORTRAN
SUBROUTINE gnome_sort(LIST, LENGTH)
INTEGER LIST, LENGTH, I, TEMP
DIMENSION LIST(LENGTH)
I = 2
DO WHILE (I .LE. LENGTH)
IF ((I .EQ. 1) .OR. (LIST(I-1) .LE. LIST(I))) THEN
I = I + 1
ELSE
TEMP = LIST(I)
LIST(I) = LIST(I-1)
LIST(I-1) = TEMP
I = I - 1
IF (I .EQ. 1) THEN
I = 2
END IF
END IF
END DO
END
Java
public class GnomeSort {
static void gnomeSort( int[] theArray ) {
for ( int index = 1; index < theArray.length; ) {
if ( theArray[index - 1] <= theArray[index] ) {
++index;
} else {
int tempVal = theArray[index];
theArray[index] = theArray[index - 1];
theArray[index - 1] = tempVal;
--index;
if ( index == 0 ) {
index = 1;
}
}
}
}
Optimized Gnome Sort in Java
This variant of Gnome Sorts allows the sorting algorithm to quickly resume the sorting process after placing n on its correct spot by skipping through the sorted portion of the array entirely, instead of looping through it, reducing comparisons.
public static int[] jumpingGnomeSort(int[] arr)
{
int n = arr.length;
int i = 0;
int prev = 0;
while (i < n)
{
if (i == 0 || arr[i] >= arr[i - 1])
{
if (prev != 0) { i += prev; prev = 0; }
++i;
}
else
{
int temp = arr[i - 1];
arr[i - 1] = arr[i];
arr[i] = temp;
++prev; --i;
}
}
return arr;
}
JavaScript
function gnomeSort(sortMe) {
i=0;
while (i < sortMe.length) {
if (i==0||sortMe[i-1] <= sortMe[i]) {
i++;
} else {
tmp=sortMe[i];
sortMe[i]=sortMe[i-1];
sortMe[--i]=tmp;
}
}
}
LavishScript
This sorts an scope-accessible index:objectype (IndexName) passed by variable name,
sorting by MemberName, which should be a numeric member of objecttype.
method Gnomesort(string IndexName, string MemberName)
{
variable int i = 1
while ${i} <= ${${IndexName}.Used}
{
if ( ${i} == 1 ) || ${${IndexName}[${Math.Calc[${i}-1]}].${MemberName}} <= ${${IndexName}[${i}].${MemberName}}
{
i:Inc
}
else
{
${IndexName}:Swap[${i}, ${Math.Calc[${i}-1]}]
i:Dec
}
}
}
Perl
sub gnome_sort(@) {
my @list = @_;
my $size = scalar(@list);
my $right = 1;
while ( $right < $size ) {
my $left = $right - 1;
if ( $list[$left] <= $list[$right] ) {
$right++;
}
else {
@list[ $left, $right ] = @list[ $right, $left ];
$right-- if $right > 1;
}
}
return @list;
}
Phix
function gnomeSort(sequence s)
integer i = 1, j = 2
while i<length(s) do
if s[i]<=s[i+1] then
i = j
j += 1
else
{s[i],s[i+1]} = {s[i+1],s[i]}
i -= 1
if i = 0 then
i = j
j += 1
end if
end if
end while
return s
end function
PHP
<?php
function gnome_sort($list)
{
for ($i = 1; $i < count($list);)
{
if ($list[$i-1] <= $list[$i]) {$i++;}
else
{
$temp = $list[$i];
$list[$i] = $list[$i-1];
$list[$i-1] = $temp;
$i--;
if ($i == 0) {$i = 1;}
}
}
return $list;
}
?>
Python
def gnomeSort(items):
i = 0
n = len(items)
while i < n:
if i and items[i] < items[i-1]:
items[i], items[i-1] = items[i-1], items[i]
i -= 1
else:
i += 1
return items
def teleportingGnomeSort(items):
i = j = 0
n = len(items)
while i < n:
if i and items[i] < items[i-1]:
items[i], items[i-1] = items[i-1], items[i]
i -= 1
else:
if i < j: # teleport!
i = j
j = i = i+1
return items
Ruby
module GnomeSort
def self.sort(keys)
sort!(keys.clone)
end
def self.sort!(keys)
i, j = 1, 2
while i < keys.size
if keys[i-1] <= keys[i]
i, j = j, j+1
else
keys[i-1], keys[i] = keys[i], keys[i-1]
i -= 1 if i > 1
end
end
keys
end
end
it:Implementazioni di algoritmi/Gnome sort