C++ Program for Stooge Sort

The Stooge sort is a recursive sorting algorithm. It is defined as below (for ascending order sorting).

Step 1 : If value at index 0 is greater than
         value at last index, swap them.
Step 2:  Recursively,
       a) Stooge sort the initial 2/3rd of the array.
       b) Stooge sort the last 2/3rd of the array.
       c) Stooge sort the initial 2/3rd again to confirm.

CPP

// C++ code to implement stooge sort
#include <iostream>
using namespace std;

// Function to implement stooge sort
void stoogesort(int arr[],int l, int h)
{
 if (l >= h)
 return;

 // If first element is smaller than last,
 // swap them
 if (arr[l] > arr[h])
 swap(arr[l], arr[h]);

 // If there are more than 2 elements in
 // the array
 if(h-l+1>2)
 {
  int t = (h-l+1)/3;

  // Recursively sort first 2/3 elements
  stoogesort(arr, l, h-t);

  // Recursively sort last 2/3 elements
  stoogesort(arr, l+t, h);

  // Recursively sort first 2/3 elements
  // again to confirm
  stoogesort(arr, l, h-t);
 }
}

// Driver Code
int main()
{
 int arr[] = {2, 4, 5, 3, 1};
 int n = sizeof(arr)/sizeof(arr[0]);

 // Calling Stooge Sort function to sort
 // the array
 stoogesort(arr, 0, n-1);

 // Display the sorted array
 for (int i=0; i<n; i++)
  cout << arr[i] << " ";

 return 0;
}

Output:

1 2 3 4 5 

Time Complexity:
The running time complexity of stooge sort can be written as,
T(n) = 3T(3n/2) + O(1)
Solution of above recurrence is O(n(log3/log1.5)) = O(n^2.709), hence it is slower than even bubble sort(n²).
Auxiliary Space: O(n)

Please refer complete article on Stooge Sort for more details!