Visualization of Stooge sort.
|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(nlog 3 / log 1.5 ) = O(n2.7095...). The running time of the algorithm is thus slower 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 3 or more elements in the list, 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
It is important to get the integer sort size used in the recursive calls by rounding the 2/3 upwards, e.g. rounding 2/3 of 5 should give 4 rather than 3, as otherwise the sort can fail on certain data. However, if the code is written to end on a base case of size 1, rather than terminating on either size 1 or size 2, rounding the 2/3 of 2 upwards gives an infinite number of calls.
function stoogesort(array L, i = 0, j = length(L)-1) if L[j] < L[i] then L[i] ↔ L[j] if (j - i + 1) > 2 then t = (j - i + 1) / 3 stoogesort(L, i , j-t) stoogesort(L, i+t, j ) stoogesort(L, i , j-t) return L
- Black, Paul E. "stooge sort". Dictionary of Algorithms and Data Structures. National Institute of Standards and Technology. Retrieved 2011-06-18.
- Cormen, Thomas H.; Leiserson, Charles E.; Rivest, Ronald L.; Stein, Clifford (2001) . "Problem 7-3". Introduction to Algorithms (2nd ed.). MIT Press and McGraw-Hill. pp. 161–162. ISBN 0-262-03293-7.
- Everything2.com – Stooge sort
- Sorting Algorithms (including Stooge sort)
- Stooge sort – implementation and comparison
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