Stooge sort

Stooge sort

Visualization of Stooge sort.
Class	Sorting algorithm
Data structure	Array
Worst case performance	O(nlog 3 /log 1.5)
Worst case space complexity	O(n)

Stooge sort is a recursive sorting algorithm with a time complexity of O(n^{log 3 / log 1.5} ) = O(n^2.7095...). The running time of the algorithm is thus extremely slow compared to efficient sorting algorithms, such as Merge sort, and is even slower than Bubble sort, a canonical example of a fairly inefficient and simple sort.

The algorithm is defined as follows:

• If the value at the end is smaller than the value at the start, swap them.
• If there are three or more elements in the current list subset, then:
  • Stooge sort the initial 2/3 of the list
  • Stooge sort the final 2/3 of the list
  • Stooge sort the initial 2/3 of the list again
• else: exit the procedure

The algorithm gets its name from slapstick routines of the Three Stooges, in which each stooge hits the other two.^{[citation needed]}

Implementation

 algorithm stoogesort(array L, i = 0, j = length(L)-1)
     if L[j] < L[i] then
         L[i] ↔ L[j]
     if (j - i + 1) >= 3 then
         t = (j - i + 1) / 3
         stoogesort(L, i  , j-t)
         stoogesort(L, i+t, j  )
         stoogesort(L, i  , j-t)
     return L

References

• Black, Paul E.. "stooge sort". Dictionary of Algorithms and Data Structures. National Institute of Standards and Technology. http://www.nist.gov/dads/HTML/stoogesort.html. Retrieved 2011-06-18. 
• Cormen, Thomas H.; Leiserson, Charles E., Rivest, Ronald L., Stein, Clifford (2001) [1990]. "Problem 7–3". Introduction to Algorithms (2nd ed.). MIT Press and McGraw-Hill. pp. 161–162. ISBN 0-262-03293-7. 

External links

• Everything2.com - Stooge sort
• Sorting Algorithms (including Stooge sort)
• Stooge sort - implementation and comparison