pancakeSort.py

# Python3 program to
# sort array using
# pancake sort

# Reverses arr[0..i] */
def flip(arr, i):
	start = 0
	while start < i:
		temp = arr[start]
		arr[start] = arr[i]
		arr[i] = temp
		start += 1
		i -= 1

# Returns index of the maximum
# element in arr[0..n-1] */
def findMax(arr, n):
	mi = 0
	for i in range(0,n):
		if arr[i] > arr[mi]:
			mi = i
	return mi

# The main function that
# sorts given array
# using flip operations
def pancakeSort(arr, n):
	
	# Start from the complete
	# array and one by one
	# reduce current size
	# by one
	curr_size = n
	while curr_size > 1:
		# Find index of the maximum
		# element in
		# arr[0..curr_size-1]
		mi = findMax(arr, curr_size)

		# Move the maximum element
		# to end of current array
		# if it's not already at
		# the end
		if mi != curr_size-1:
			# To move at the end,
			# first move maximum
			# number to beginning
			flip(arr, mi)

			# Now move the maximum
			# number to end by
			# reversing current array
			flip(arr, curr_size-1)
		curr_size -= 1

# A utility function to
# print an array of size n
def printArray(arr, n):
	for i in range(0,n):
		print ("%d"%( arr[i]),end=" ")

# Driver program
arr = [23, 10, 20, 11, 12, 6, 7]
n = len(arr)
pancakeSort(arr, n);
print ("Sorted Array ")
printArray(arr,n)