cocktail-sort.py

# Python program for implementation of Cocktail Sort

def cocktailSort(a):
	n = len(a)
	swapped = True
	start = 0
	end = n-1
	while (swapped==True):

		# reset the swapped flag on entering the loop,
		# because it might be true from a previous
		# iteration.
		swapped = False

		# loop from left to right same as the bubble
		# sort
		for i in range (start, end):
			if (a[i] > a[i+1]) :
				a[i], a[i+1]= a[i+1], a[i]
				swapped=True

		# if nothing moved, then array is sorted.
		if (swapped==False):
			break

		# otherwise, reset the swapped flag so that it
		# can be used in the next stage
		swapped = False

		# move the end point back by one, because
		# item at the end is in its rightful spot
		end = end-1

		# from right to left, doing the same
		# comparison as in the previous stage
		for i in range(end-1, start-1,-1):
			if (a[i] > a[i+1]):
				a[i], a[i+1] = a[i+1], a[i]
				swapped = True

		# increase the starting point, because
		# the last stage would have moved the next
		# smallest number to its rightful spot.
		start = start+1

# Driver code to test above
a = [5, 1, 4, 2, 8, 0, 2]
cocktailSort(a)
print("Sorted array is:")
for i in range(len(a)):
	print ("%d" %a[i]),