# Pancake sorting

Given an unsorted array, the task is to sort the given array. You are allowed to do only following operation on array.

• flip(arr, i): Reverse array from 0 to i

Examples:

Input: arr[] = { 23, 10, 20, 11, 12, 6, 7 }
Output: { 6, 7, 10, 11, 12, 20, 23}

Input: arr[] = { 0, 1, 1, 0, 0 }
Output: { 0, 0, 0, 1, 1 }

Approach: Unlike a traditional sorting algorithm, which attempts to sort with the fewest comparisons possible, the goal is to sort the sequence in as few reversals as possible.

The idea is to do something similar to Selection Sort. We one by one place maximum element at the end and reduce the size of current array by one.

Following are the detailed steps. Let given array be arr[] and size of array be n.

• Start from current size equal to n and reduce current size by one while it’s greater than 1. Let the current size be curr_size.
• Do following for every curr_size
• Find index of the maximum element in arr[0 to curr_szie-1]. Let the index be ‘mi’
• Call flip(arr, mi)
• Call flip(arr, curr_size – 1)

See following video for visualization of the above algorithm.

Below is the implementation:

## C

 `// C program to` `// sort array using` `// pancake sort` `#include ` `#include `   `/* Reverses arr[0..i] */` `void` `flip(``int` `arr[], ``int` `i)` `{` `    ``int` `temp, start = 0;` `    ``while` `(start < i) {` `        ``temp = arr[start];` `        ``arr[start] = arr[i];` `        ``arr[i] = temp;` `        ``start++;` `        ``i--;` `    ``}` `}`   `// Returns index of the` `// maximum element in` `// arr[0..n-1]` `int` `findMax(``int` `arr[], ``int` `n)` `{` `    ``int` `mi, i;` `    ``for` `(mi = 0, i = 0; i < n; ++i)` `        ``if` `(arr[i] > arr[mi])` `            ``mi = i;` `    ``return` `mi;` `}`   `// The main function that` `// sorts given array using` `// flip operations` `void` `pancakeSort(``int``* arr, ``int` `n)` `{` `    ``// Start from the complete` `    ``// array and one by one` `    ``// reduce current size` `    ``// by one` `    ``for` `(``int` `curr_size = n; curr_size > 1; ` `                                 ``--curr_size) ` `    ``{` `        ``// Find index of the` `        ``// maximum element in` `        ``// arr[0..curr_size-1]` `        ``int` `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);` `        ``}` `    ``}` `}`   `// A utility function to print` `// n array of size n` `void` `printArray(``int` `arr[], ``int` `n)` `{` `    ``for` `(``int` `i = 0; i < n; ++i)` `        ``printf``(``"%d "``, arr[i]);` `}`   `// Driver program to test above function` `int` `main()` `{` `    ``int` `arr[] = { 23, 10, 20, 11, 12, 6, 7 };` `    ``int` `n = ``sizeof``(arr) / ``sizeof``(arr[0]);`   `    ``pancakeSort(arr, n);`   `    ``puts``(``"Sorted Array "``);` `    ``printArray(arr, n);`   `    ``return` `0;` `}`

## CPP

 `// C++ program to ` `// sort array using ` `// pancake sort ` `#include ` `using` `namespace` `std; `   `/* Reverses arr[0..i] */` `void` `flip(``int` `arr[], ``int` `i) ` `{ ` `    ``int` `temp, start = 0; ` `    ``while` `(start < i) ` `    ``{ ` `        ``temp = arr[start]; ` `        ``arr[start] = arr[i]; ` `        ``arr[i] = temp; ` `        ``start++; ` `        ``i--; ` `    ``} ` `} `   `// Returns index of the ` `// maximum element in ` `// arr[0..n-1] ` `int` `findMax(``int` `arr[], ``int` `n) ` `{ ` `int` `mi, i; ` `for` `(mi = 0, i = 0; i < n; ++i) ` `    ``if` `(arr[i] > arr[mi]) ` `            ``mi = i; ` `return` `mi; ` `} `   `// The main function that ` `// sorts given array using ` `// flip operations ` `void` `pancakeSort(``int` `*arr, ``int` `n) ` `{ ` `    ``// Start from the complete ` `    ``// array and one by one ` `    ``// reduce current size ` `    ``// by one ` `    ``for` `(``int` `curr_size = n; curr_size > 1; ` `                               ``--curr_size) ` `    ``{ ` `        ``// Find index of the ` `        ``// maximum element in ` `        ``// arr[0..curr_size-1] ` `        ``int` `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); ` `        ``} ` `    ``} ` `} `   `// A utility function to print ` `// n array of size n ` `void` `printArray(``int` `arr[], ``int` `n) ` `{ ` `    ``for` `(``int` `i = 0; i < n; ++i) ` `        ``cout<< arr[i]<<``" "``; ` `} `   `// Driver program to test above function ` `int` `main() ` `{ ` `    ``int` `arr[] = {23, 10, 20, 11, 12, 6, 7}; ` `    ``int` `n = ``sizeof``(arr)/``sizeof``(arr[0]); `   `    ``pancakeSort(arr, n); `   `    ``cout<<``"Sorted Array "``<

## Java

 `// Java program to` `// sort array using` `// pancake sort` `import` `java.io.*;`   `class` `PancakeSort {`   `    ``/* Reverses arr[0..i] */` `    ``static` `void` `flip(``int` `arr[], ``int` `i)` `    ``{` `        ``int` `temp, start = ``0``;` `        ``while` `(start < i)` `        ``{` `            ``temp = arr[start];` `            ``arr[start] = arr[i];` `            ``arr[i] = temp;` `            ``start++;` `            ``i--;` `        ``}` `    ``}`   `    ``// Returns index of the ` `    ``// maximum element in ` `    ``// arr[0..n-1] ` `    ``static` `int` `findMax(``int` `arr[], ``int` `n)` `    ``{` `        ``int` `mi, i;` `        ``for` `(mi = ``0``, i = ``0``; i < n; ++i)` `            ``if` `(arr[i] > arr[mi])` `                ``mi = i;` `        ``return` `mi;` `    ``}`   `    ``// The main function that` `    ``// sorts given array using ` `    ``// flip operations` `    ``static` `int` `pancakeSort(``int` `arr[], ``int` `n)` `    ``{` `        ``// Start from the complete` `        ``// array and one by one` `        ``// reduce current size by one` `        ``for` `(``int` `curr_size = n; curr_size > ``1``; ` `                                 ``--curr_size)` `        ``{` `            ``// Find index of the` `            ``// maximum element in` `            ``// arr[0..curr_size-1]` `            ``int` `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``);` `            ``}` `        ``}` `        ``return` `0``;` `    ``}`   `    ``/* Utility function to print array arr[] */` `    ``static` `void` `printArray(``int` `arr[], ``int` `arr_size)` `    ``{` `        ``for` `(``int` `i = ``0``; i < arr_size; i++)` `            ``System.out.print(arr[i] + ``" "``);` `        ``System.out.println(``""``);` `    ``}`   `    ``/* Driver function to check for above functions*/` `    ``public` `static` `void` `main (String[] args)` `    ``{` `        ``int` `arr[] = {``23``, ``10``, ``20``, ``11``, ``12``, ``6``, ``7``};` `        ``int` `n = arr.length;` `        `  `        ``pancakeSort(arr, n);` `        `  `        ``System.out.println(``"Sorted Array: "``);` `        ``printArray(arr, n);` `    ``}` `}` `/* This code is contributed by Devesh Agrawal*/`

## Python3

 `# 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)`   `# This code is contributed by shreyanshi_arun.`

## C#

 `// C# program to sort array using` `// pancake sort` `using` `System;`   `class` `GFG {`   `    ``// Reverses arr[0..i]` `    ``static` `void` `flip(``int` `[]arr, ``int` `i)` `    ``{` `        ``int` `temp, start = 0;` `        ``while` `(start < i)` `        ``{` `            ``temp = arr[start];` `            ``arr[start] = arr[i];` `            ``arr[i] = temp;` `            ``start++;` `            ``i--;` `        ``}` `    ``}`   `    ``// Returns index of the ` `    ``// maximum element in ` `    ``// arr[0..n-1] ` `    ``static` `int` `findMax(``int` `[]arr, ``int` `n)` `    ``{` `        ``int` `mi, i;` `        ``for` `(mi = 0, i = 0; i < n; ++i)` `            ``if` `(arr[i] > arr[mi])` `                ``mi = i;` `                `  `        ``return` `mi;` `    ``}`   `    ``// The main function that` `    ``// sorts given array using ` `    ``// flip operations` `    ``static` `int` `pancakeSort(``int` `[]arr, ``int` `n)` `    ``{` `        `  `        ``// Start from the complete` `        ``// array and one by one` `        ``// reduce current size by one` `        ``for` `(``int` `curr_size = n; curr_size > 1;` `                                  ``--curr_size)` `        ``{` `            `  `            ``// Find index of the` `            ``// maximum element in` `            ``// arr[0..curr_size-1]` `            ``int` `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);` `            ``}` `        ``}` `        `  `        ``return` `0;` `    ``}`   `    ``// Utility function to print` `    ``// array arr[]` `    ``static` `void` `printArray(``int` `[]arr,` `                           ``int` `arr_size)` `    ``{` `        ``for` `(``int` `i = 0; i < arr_size; i++)` `            ``Console.Write(arr[i] + ``" "``);` `            `  `        ``Console.Write(``""``);` `    ``}`   `    ``// Driver function to check for ` `    ``// above functions` `    ``public` `static` `void` `Main ()` `    ``{` `        ``int` `[]arr = {23, 10, 20, 11, 12, 6, 7};` `        ``int` `n = arr.Length;` `        `  `        ``pancakeSort(arr, n);` `        `  `        ``Console.Write(``"Sorted Array: "``);` `        ``printArray(arr, n);` `    ``}` `}`   `// This code is contributed by nitin mittal.`

## PHP

 ` ``\$arr``[``\$mi``])` `                ``\$mi` `= ``\$i``;` `    ``return` `\$mi``;` `}`   `// The main function that ` `// sorts given array using ` `// flip operations` `function` `pancakeSort(&``\$arr``, ``\$n``)` `{` `    ``// Start from the complete` `    ``// array and one by one ` `    ``// reduce current size ` `    ``// by one` `    ``for` `(``\$curr_size` `= ``\$n``; ``\$curr_size` `> 1; ` `                              ``--``\$curr_size``)` `    ``{` `        ``// 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);` `        ``}` `    ``}` `}`   `// A utility function to print ` `// n array of size n ` `function` `printArray(``\$arr``, ``\$n``)` `{` `    ``for` `(``\$i` `= 0; ``\$i` `< ``\$n``; ++``\$i``)` `        ``print``(``\$arr``[``\$i``].``" "``);` `}`   `// Driver code` `\$arr` `= ``array``(23, 10, 20, 11, 12, 6, 7);` `\$n` `= ``count``(``\$arr``);`   `pancakeSort(``\$arr``, ``\$n``);`   `echo``(``"Sorted Array \n"``);` `printArray(``\$arr``, ``\$n``);`   `return` `0;` `    `  `// This code is contributed by chandan_jnu` `?>`

## Javascript

 ``

Output

```Sorted Array
6 7 10 11 12 20 23 ```

Time Complexity: O(n2), Total O(n) flip operations are performed in above code
Auxiliary Space: O(1)

### Recursive Approach

Another approach to implement pancake sort in C++ is by using a recursive algorithm .

Approach :

Step 1: Define a function to flip a subarray of the given array. This function takes two arguments: the array to be flipped, and the index of the last element of the subarray to be flipped.

Step 2: Define a function to find the index of the maximum element in a given subarray of the array. This function takes two arguments: the array to be searched, and the index of the last element of the subarray to be searched.

Step 3: Iterate over the input array from the end towards the beginning, and for each element i, do the following:

• Find the index of the maximum element in the subarray arr[0:i].
• If the maximum element is not already at the end of the subarray, flip the subarray arr[0:max_index].
• Flip the entire subarray arr[0:i] to move the element i to its correct position.

Step 4: Repeat Step 3 for the subarray arr[0:n-1], arr[0:n-2], …, arr[0:1] until the entire array is sorted.

## C++

 `#include ` `using` `namespace` `std;`   `// Reverses arr[0..i]` `void` `flip(``int` `arr[], ``int` `i)` `{` `    ``int` `temp, start = 0;` `    ``while` `(start < i) {` `        ``temp = arr[start];` `        ``arr[start] = arr[i];` `        ``arr[i] = temp;` `        ``start++;` `        ``i--;` `    ``}` `}`   `// Recursive function to sort the array using pancake sort` `void` `pancakeSort(``int` `arr[], ``int` `n)` `{` `    ``// Base case: If the array is already sorted or has only` `    ``// one element, return` `    ``if` `(n == 1)` `        ``return``;`   `    ``// Find the index of the maximum element in the unsorted` `    ``// portion of the array` `    ``int` `mi = 0;` `    ``for` `(``int` `i = 0; i < n; i++) {` `        ``if` `(arr[i] > arr[mi]) {` `            ``mi = i;` `        ``}` `    ``}`   `    ``// Move the maximum element to the front of the array if` `    ``// it's not already there` `    ``if` `(mi != 0) {` `        ``flip(arr, mi);` `    ``}`   `    ``// Flip the entire array to move the maximum element to` `    ``// its correct position` `    ``flip(arr, n - 1);`   `    ``// Recursively sort the remaining unsorted portion of` `    ``// the array` `    ``pancakeSort(arr, n - 1);` `}`   `// Driver program to test above function` `int` `main()` `{` `    ``int` `arr[] = { 23, 10, 20, 11, 12, 6, 7 };` `    ``int` `n = ``sizeof``(arr) / ``sizeof``(arr[0]);`   `    ``pancakeSort(arr, n);`   `    ``cout << ``"Sorted Array: "``;` `    ``for` `(``int` `i = 0; i < n; i++) {` `        ``cout << arr[i] << ``" "``;` `    ``}` `    ``cout << endl;`   `    ``return` `0;` `}`

## Java

 `import` `java.util.*;`   `public` `class` `PancakeSort {` `    ``// Reverses arr[0..i]` `    ``static` `void` `flip(``int` `arr[], ``int` `i)` `    ``{` `        ``int` `temp, start = ``0``;` `        ``while` `(start < i) {` `            ``temp = arr[start];` `            ``arr[start] = arr[i];` `            ``arr[i] = temp;` `            ``start++;` `            ``i--;` `        ``}` `    ``}`   `    ``// Recursive function to sort the array using pancake` `    ``// sort` `    ``static` `void` `pancakeSort(``int` `arr[], ``int` `n)` `    ``{` `        ``// Base case: If the array is already sorted or has` `        ``// only one element, return` `        ``if` `(n == ``1``)` `            ``return``;`   `        ``// Find the index of the maximum element in the` `        ``// unsorted portion of the array` `        ``int` `mi = ``0``;` `        ``for` `(``int` `i = ``0``; i < n; i++) {` `            ``if` `(arr[i] > arr[mi]) {` `                ``mi = i;` `            ``}` `        ``}`   `        ``// Move the maximum element to the front of the` `        ``// array if it's not already there` `        ``if` `(mi != ``0``) {` `            ``flip(arr, mi);` `        ``}`   `        ``// Flip the entire array to move the maximum element` `        ``// to its correct position` `        ``flip(arr, n - ``1``);`   `        ``// Recursively sort the remaining unsorted portion` `        ``// of the array` `        ``pancakeSort(arr, n - ``1``);` `    ``}`   `    ``// Driver program to test above function` `    ``public` `static` `void` `main(String args[])` `    ``{` `        ``int` `arr[] = { ``23``, ``10``, ``20``, ``11``, ``12``, ``6``, ``7` `};` `        ``int` `n = arr.length;`   `        ``pancakeSort(arr, n);`   `        ``System.out.print(``"Sorted Array: "``);` `        ``for` `(``int` `i = ``0``; i < n; i++) {` `            ``System.out.print(arr[i] + ``" "``);` `        ``}` `        ``System.out.println();` `    ``}` `}`   `// Contributed by sdeadityasharma`

## Python3

 `# Python code addition `   `# 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`   `# Recursive function to sort the array using pancake sort` `def` `pancakeSort(arr, n):` `    ``# Base case: If the array is already sorted or has only` `    ``# one element, return` `    ``if` `n ``=``=` `1``:` `        ``return`   `    ``# Find the index of the maximum element in the unsorted` `    ``# portion of the array` `    ``mi ``=` `0` `    ``for` `i ``in` `range``(n):` `        ``if` `arr[i] > arr[mi]:` `            ``mi ``=` `i`   `    ``# Move the maximum element to the front of the array if` `    ``# it's not already there` `    ``if` `mi !``=` `0``:` `        ``flip(arr, mi)`   `    ``# Flip the entire array to move the maximum element to` `    ``# its correct position` `    ``flip(arr, n ``-` `1``)`   `    ``# Recursively sort the remaining unsorted portion of` `    ``# the array` `    ``pancakeSort(arr, n ``-` `1``)`   `# Driver program to test above function` `arr ``=` `[``23``, ``10``, ``20``, ``11``, ``12``, ``6``, ``7``]` `n ``=` `len``(arr)`   `pancakeSort(arr, n)`   `print``(``"Sorted Array:"``, end``=``" "``)` `for` `i ``in` `range``(n):` `    ``print``(arr[i], end``=``" "``)` `print``()`   `# The code is contributed by Nidhi goel.`

## C#

 `using` `System;`   `class` `Program {` `    ``// Reverses arr[0..i]` `    ``static` `void` `Flip(``int``[] arr, ``int` `i)` `    ``{` `        ``int` `temp, start = 0;` `        ``while` `(start < i) {` `            ``temp = arr[start];` `            ``arr[start] = arr[i];` `            ``arr[i] = temp;` `            ``start++;` `            ``i--;` `        ``}` `    ``}`   `    ``// Recursive function to sort the array using pancake` `    ``// sort` `    ``static` `void` `PancakeSort(``int``[] arr, ``int` `n)` `    ``{` `        ``// Base case: If the array is already sorted or has` `        ``// only one element, return` `        ``if` `(n == 1)` `            ``return``;`   `        ``// Find the index of the maximum element in the` `        ``// unsorted portion of the array` `        ``int` `mi = 0;` `        ``for` `(``int` `i = 0; i < n; i++) {` `            ``if` `(arr[i] > arr[mi]) {` `                ``mi = i;` `            ``}` `        ``}`   `        ``// Move the maximum element to the front of the` `        ``// array if it's not already there` `        ``if` `(mi != 0) {` `            ``Flip(arr, mi);` `        ``}`   `        ``// Flip the entire array to move the maximum element` `        ``// to its correct position` `        ``Flip(arr, n - 1);`   `        ``// Recursively sort the remaining unsorted portion` `        ``// of the array` `        ``PancakeSort(arr, n - 1);` `    ``}`   `    ``// Driver program to test above function` `    ``static` `void` `Main()` `    ``{` `        ``int``[] arr = { 23, 10, 20, 11, 12, 6, 7 };` `        ``int` `n = arr.Length;`   `        ``PancakeSort(arr, n);`   `        ``Console.Write(``"Sorted Array: "``);` `        ``for` `(``int` `i = 0; i < n; i++) {` `            ``Console.Write(arr[i] + ``" "``);` `        ``}` `        ``Console.WriteLine();` `    ``}` `}` `// This code is contributed by sarojmcy2e`

## Javascript

 `// Reverses arr[0..i]` `function` `flip(arr, i) {` `    ``let start = 0;` `    ``while` `(start < i) {` `        ``let temp = arr[start];` `        ``arr[start] = arr[i];` `        ``arr[i] = temp;` `        ``start++;` `        ``i--;` `    ``}` `}` `// Recursive function to sort the array using pancake sort` `function` `pancakeSort(arr, n) {` `    ``if` `(n === 1) {` `        ``// Base case: If the array is already sorted or has only one element, return` `        ``return``;` `    ``}` `    `  `    ``// Find the index of the maximum element in the unsorted portion of the array` `    ``let mi = 0;` `    ``for` `(let i = 0; i < n; i++) {` `        ``if` `(arr[i] > arr[mi]) {` `            ``mi = i;` `        ``}` `    ``}`   `    ``// Move the maximum element to the front of the array if it's not already there` `    ``if` `(mi !== 0) {` `        ``flip(arr, mi);` `    ``}` `    ``// Flip the entire array to move the maximum element to its correct position` `    ``flip(arr, n - 1);` `    ``// Recursively sort the remaining unsorted portion of the array` `    ``pancakeSort(arr, n - 1);` `}`   `let arr = [23, 10, 20, 11, 12, 6, 7];` `let n = arr.length;` `pancakeSort(arr, n);` `console.log(``"Sorted Array: "` `+ arr.join(``" "``));`   `// This code is contributed by shiv1o43g`

Output

`Sorted Array: 6 7 10 11 12 20 23 `

#### Complexity Analysis:

• The time complexity of pancake sort is O(n2), where n is the size of the input array. The worst case occurs when the input array is reverse sorted.
• The space complexity is O(1) since the sorting is done in-place.

References:
http://en.wikipedia.org/wiki/Pancake_sorting