Python: Sort a list of elements using Pancake sort

Last update on April 23 2025 12:56:53 (UTC/GMT +8 hours)

18. Pancake Sort

Write a Python program to sort a list of elements using Pancake sort.
Pancake sorting is the colloquial term for the mathematical problem of sorting a disordered stack of pancakes in order of size when a spatula can be inserted at any point in the stack and used to flip all pancakes above it. A pancake number is the minimum number of flips required for a given number of pancakes. The problem was first discussed by American geometer Jacob E. Goodman. It is a variation of the sorting problem in which the only allowed operation is to reverse the elements of some prefix of the sequence.

Sample Solution:

Python Code:

def pancake_sort(nums):
    arr_len = len(nums)
    while arr_len > 1:
        mi = nums.index(max(nums[0:arr_len]))
        nums = nums[mi::-1] + nums[mi+1:len(nums)]
        nums = nums[arr_len-1::-1] + nums[arr_len:len(nums)]
        arr_len -= 1
    return nums

user_input = input("Input numbers separated by a comma:\n").strip()
nums = [int(item) for item in user_input.split(',')]
print(pancake_sort(nums))

Sample Output:

Input numbers separated by a comma:
 15, 79, 25, 38, 69
[15, 25, 38, 69, 79]

Flowchart:

For more Practice: Solve these Related Problems:

Write a Python program to implement pancake sort and print the flip sequence required to sort the list.
Write a Python script to perform pancake sort on an array and display intermediate pancake flips at each step.
Write a Python program to sort a list using pancake sort and then count the total number of flips performed.
Write a Python function to implement pancake sort on a list of numbers and then verify the sorted output by reversing the flips.

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