
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:

O(n logn) sorts
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


Task

Sort an array of positive integers using the Bead Sort Algorithm.

A   bead sort   is also known as a   gravity sort.



Algorithm has   O(S),   where   S   is the sum of the integers in the input set:   Each bead is moved individually.

This is the case when bead sort is implemented without a mechanism to assist in finding empty spaces below the beads, such as in software implementations.




 
class
	BEAD_SORT
 
feature
 
	bead_sort (ar: ARRAY [INTEGER]): ARRAY [INTEGER]
			-- Sorted array in descending order.
		require
			only_positive_integers: across ar as a all a.item > 0 end
		local
			max, count, i, j, k: INTEGER
		do
			max := max_item (ar)
			create Result.make_filled (0, 1, ar.count)
			from
				i := 1
			until
				i > max
			loop
				count := 0
				from
					k := 1
				until
					k > ar.count
				loop
					if ar.item (k) >= i then
						count := count + 1
					end
					k := k + 1
				end
				from
					j := 1
				until
					j > count
				loop
					Result [j] := i
					j := j + 1
				end
				i := i + 1
			end
		ensure
			array_is_sorted: is_sorted (Result)
		end
 
feature {NONE}
 
	max_item (ar: ARRAY [INTEGER]): INTEGER
			-- Max item of 'ar'.
		require
			ar_not_void: ar /= Void
		do
			across
				ar as a
			loop
				if a.item > Result then
					Result := a.item
				end
			end
		ensure
			Result_is_max: across ar as a all a.item <= Result end
		end
 
	is_sorted (ar: ARRAY [INTEGER]): BOOLEAN
			--- Is 'ar' sorted in descending order?
		require
			ar_not_empty: ar.is_empty = False
		local
			i: INTEGER
		do
			Result := True
			from
				i := ar.lower
			until
				i = ar.upper
			loop
				if ar [i] < ar [i + 1] then
					Result := False
				end
				i := i + 1
			end
		end
 
end
 