Sorting algorithms/Comb sort
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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.
Psuedocode
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
Implementations
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>
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>
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