Are there any worse sorting algorithms than Bogosort (a.k.a Monkey Sort)? [closed]

Answer 1

My favorite slow sorting algorithm is the stooge sort:

void stooges(long *begin, long *end) {
   if( (end-begin) <= 1 ) return;
   if( begin[0] < end[-1] ) swap(begin, end-1);
   if( (end-begin) > 1 ) {
      int one_third = (end-begin)/3;
      stooges(begin, end-one_third);
      stooges(begin+one_third, end);
      stooges(begin, end-one_third);
   }
}

The worst case complexity is O(n^(log(3) / log(1.5))) = O(n^2.7095...).

Another slow sorting algorithm is actually named slowsort!

void slow(long *start, long *end) {
   if( (end-start) <= 1 ) return;
   long *middle = start + (end-start)/2;
   slow(start, middle);
   slow(middle, end);
   if( middle[-1] > end[-1] ) swap(middle-1, end-1);
   slow(start, end-1);
}

This one takes O(n ^ (log n)) in the best case... even slower than stoogesort.

Answer 2

Double bogosort

Bogosort twice and compare results (just to be sure it is sorted) if not do it again

Answer 3

I'm surprised no one has mentioned sleepsort yet... Or haven't I noticed it? Anyway:

#!/bin/bash
function f() {
    sleep "$1"
    echo "$1"
}
while [ -n "$1" ]
do
    f "$1" &
    shift
done
wait

example usage:

./sleepsort.sh 5 3 6 3 6 3 1 4 7
./sleepsort.sh 8864569 7

In terms of performance it is terrible (especially the second example). Waiting almost 3.5 months to sort 2 numbers is kinda bad.

Answer 4

Randomsubsetsort.

Given an array of n elements, choose each element with probability 1/n, randomize these elements, and check if the array is sorted. Repeat until sorted.

Expected time is left as an exercise for the reader.

Answer 5

If you keep the algorithm meaningful in any way, O(n!) is the worst upper bound you can achieve.

Since checking each possibility for a permutations of a set to be sorted will take n! steps, you can't get any worse than that.

If you're doing more steps than that then the algorithm has no real useful purpose. Not to mention the following simple sorting algorithm with O(infinity):

list = someList
while (list not sorted):
    doNothing

Answer 6

Quantum Bogosort

A sorting algorithm that assumes that the many-worlds interpretation of quantum mechanics is correct:

1. Check that the list is sorted. If not, destroy the universe.

At the conclusion of the algorithm, the list will be sorted in the only universe left standing. This algorithm takes worst-case O(N) and average-case O(1) time. In fact, the average number of comparisons performed is 2: there's a 50% chance that the universe will be destroyed on the second element, a 25% chance that it'll be destroyed on the third, and so on.