Sorting algorithms/Comb sort
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
The Comb Sort is a variant of the Bubble Sort. Like the Shell sort, the Comb Sort increases the gap used in comparisons and exchanges (dividing the gap by works best, but 1.3 may be more practical). Some implementations use the insertion sort once the gap is less than a certain amount. See the article on Wikipedia.
Variants:
- Combsort11 makes sure the gap ends in (11, 8, 6, 4, 3, 2, 1), which is significantly faster than the other two possible endings
- Combsort with different endings changes to a more efficient sort when the data is almost sorted (when the gap is small). Comb sort with a low gap isn't much better than the Bubble Sort.
Pseudocode:
function combsort(array input) gap := input.size //initialize gap size loop until gap <= 1 and swaps = 0 //update the gap value for a next comb. Below is an example gap := int(gap / 1.25) i := 0 swaps := 0 //see Bubble Sort for an explanation //a single "comb" over the input list loop until i + gap >= input.size //see Shell sort for similar idea if input[i] > input[i+gap] swap(input[i], input[i+gap]) swaps := 1 // Flag a swap has occurred, so the // list is not guaranteed sorted end if i := i + 1 end loop end loop end function
C
Implementation of Combsort11. Its efficiency can be improved by just switching to Insertion sort when the gap size becomes less than 10. <lang c>void Combsort11(double a[], int nElements) {
int i, j, gap, swapped = 1; double temp;
gap = nElements; while (gap > 1 || swapped == 1) { gap = gap * 10 / 13; if (gap == 9 || gap == 10) gap = 11; if (gap < 1) gap = 1; swapped = 0; for (i = 0, j = gap; j < nElements; i++, j++) { if (a[i] > a[j]) { temp = a[i]; a[i] = a[j]; a[j] = temp; swapped = 1; } } }
}</lang>
C++
This is copied from the Wikipedia article. <lang cpp>template<class ForwardIterator> void combsort ( ForwardIterator first, ForwardIterator last ) {
static const double shrink_factor = 1.247330950103979; typedef typename std::iterator_traits<ForwardIterator>::difference_type difference_type; difference_type gap = std::distance(first, last); bool swaps = true; while ( (gap > 1) || (swaps == true) ){ if (gap > 1) gap = static_cast<difference_type>(gap/shrink_factor); swaps = false; ForwardIterator itLeft(first); ForwardIterator itRight(first); std::advance(itRight, gap); for ( ; itRight!=last; ++itLeft, ++itRight ){ if ( (*itRight) < (*itLeft) ){ std::iter_swap(itLeft, itRight); swaps = true; } } }
}</lang>
J
Large gap sizes allow some parallelism in comparisons and swaps. Beyond that, however, the data flow complexity of this algorithm requires a fair bit of micro-management.
<lang J>combSort=:3 :0
gap=. #y whilst.1 < gap+swaps do. swaps=. 0 i=. i.2,gap=. 1 >. <.gap%1.25 while.{:$i=.i #"1~ ({: i) < #y do. swaps=.swaps+#{:k=.i #"1~b=. >/ i{y i=. i+gap y=.((|.k){y) k} y end. end. y
)</lang>
Example use:
combSort 23 76 99 58 97 57 35 89 51 38 95 92 24 46 31 24 14 12 57 78 12 14 23 24 24 31 35 38 46 51 57 57 58 76 78 89 92 95 97 99
Java
This is copied from the Wikipedia article. <lang java>public static void sort(Comparable[] input) {
int gap = input.length; boolean swapped = true; while (gap > 1 || swapped) { if (gap > 1) { gap = (int) (gap / 1.3); } int i = 0; swapped = false; while (i + gap < input.length) { if (input[i].compareTo(input[i + gap]) > 0) { Comparable t = input[i]; input[i] = input[i + gap]; input[i + gap] = t; swapped = true; } i++; } }
}</lang>
Lua
<lang lua>function combsort(t)
local gapd, gap, swaps = 1.2473, #t, 0 while gap + swaps > 1 do local k = 0 swaps = 0 if gap > 1 then gap = math.floor(gap / gapd) end for k = 1, #t - gap do if t[k] > t[k + gap] then t[k], t[k + gap], swaps = t[k + gap], t[k], swaps + 1 end end end return t
end
print(unpack(combsort{3,5,1,2,7,4,8,3,6,4,1}))</lang>
OCaml
<lang ocaml>let comb_sort ~input =
let input_length = Array.length input in let gap = ref(input_length) in let swapped = ref true in while (!gap > 1 || !swapped) do if (!gap > 1) then gap := int_of_float (float !gap /. 1.3);
let i = ref 0 in swapped := false; while (!i + !gap < input_length) do if input.(!i) > input.(!i + !gap) then begin let tmp = input.(!i) in input.(!i) <- input.(!i + !gap); input.(!i + !gap) <- tmp; swapped := true; end; incr i; done done
- </lang>
Oz
<lang oz>declare
proc {CombSort Arr} Low = {Array.low Arr} High = {Array.high Arr} Size = High - Low + 1 Gap = {NewCell Size} Swapped = {NewCell true} proc {Swap I J} Arr.J := (Arr.I := Arr.J) end in for while:@Gap>1 orelse @Swapped do if @Gap > 1 then Gap := {Float.toInt {Floor {Int.toFloat @Gap} / 1.3}} end Swapped := false for I in Low..High-@Gap do if Arr.I > Arr.(I+@Gap) then {Swap I I+@Gap} Swapped := true end end end end Arr = {Tuple.toArray unit(3 1 4 1 5 9 2 6 5)}
in
{CombSort Arr} {Show {Array.toRecord unit Arr}}</lang>
Ruby
<lang ruby>class Array
def combsort! gap = size swaps = true until gap <= 1 and swaps gap = (gap / 1.25).to_int swaps = false 0.upto(size - gap - 1) do |i| if self[i] > self[i+gap] self[i], self[i+gap] = self[i+gap], self[i] swaps = true end end end self end
end
p [23, 76, 99, 58, 97, 57, 35, 89, 51, 38, 95, 92, 24, 46, 31, 24, 14, 12, 57, 78].combsort!</lang> results in
[12, 14, 23, 24, 24, 31, 35, 38, 46, 51, 57, 57, 58, 76, 78, 89, 92, 95, 97, 99]
Tcl
<lang tcl>proc combsort {input} {
set gap [llength $input] while 1 {
set gap [expr {int(floor($gap / 1.3))}] set swaps 0 for {set i 0} {$i+$gap < [llength $input]} {incr i} { set j [expr {$i+$gap}] if {[lindex $input $i] > [lindex $input $j]} { set tmp [lindex $input $i] lset input $i [lindex $input $j] lset input $j $tmp incr swaps } } if {$gap <= 1 && !$swaps} break
} return $input
}
set data {23 76 99 58 97 57 35 89 51 38 95 92 24 46 31 24 14 12 57 78} puts [combsort $data]</lang> Produces this output:
12 14 23 24 24 31 35 38 46 51 57 57 58 76 78 89 92 95 97 99
TI-83 BASIC
Requires prgmSORTINS. Gap division of 1.3. Switches to Insertion sort when gap is less than 5.
:L1→L2 :dim(L2)→A :While A>5 and B=0 :int(A/1.3)→A :1→C :0→B :While (C+A)≥dim(L2) :If L2(C)>L2(C+A) :Then :L2(C)→D :L2(C+A)→L2(C) :D→L2(C+A) :1→B :End :C+1→C :End :DelVar A :DelVar B :DelVar C :DelVar D :L1→L3 :L2→L1 :prgmSORTINS :L3→L1 :DelVar L3 :Stop