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Python Program for BogoSort or Permutation Sort

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BogoSort also known as permutation sort, stupid sort, slow sort, shotgun sort or monkey sort is a particularly ineffective algorithm based on generate and test paradigm. The algorithm successively generates permutations of its input until it finds one that is sorted.(Wiki
For example, if bogosort is used to sort a deck of cards, it would consist of checking if the deck were in order, and if it were not, one would throw the deck into the air, pick the cards up at random, and repeat the process until the deck is sorted. 
PseudoCode: 
 

while not Sorted(list) do
    shuffle (list)
done

 

Python3




# Python program for implementation of Bogo Sort
import random
 
# Sorts array a[0..n-1] using Bogo sort
def bogoSort(a):
    n = len(a)
    while (is_sorted(a)== False):
        shuffle(a)
 
# To check if array is sorted or not
def is_sorted(a):
    n = len(a)
    for i in range(0, n-1):
        if (a[i] > a[i+1] ):
            return False
    return True
 
# To generate permutation of the array
def shuffle(a):
    n = len(a)
    for i in range (0,n):
        r = random.randint(0,n-1)
        a[i], a[r] = a[r], a[i]
 
# Driver code to test above
a = [3, 2, 4, 1, 0, 5]
bogoSort(a)
print("Sorted array :")
for i in range(len(a)):
    print ("%d" %a[i]),

Output: 
 

Sorted array :
0
1
2
3
4
5

Time Complexity:

Worst Case: O(∞) (since this algorithm has no upper bound)
Average Case: O(n*n!)
Best Case: O(n)(when the array given is already sorted)

Auxiliary Space: O(1)

Method 2: BogoSort implementation using builtin shuffle() and sorted() function

In this implementation, the sorted built-in function is used to check if the list is sorted or not. The random.shuffle function is used to generate a permutation of the array a.

Python3




import random
  
# Sorts array a[0..n-1] using Bogo sort
def bogoSort(a):
    n = len(a)
    while not sorted(a) == a:
        random.shuffle(a)
  
# Driver code to test above
a = [3, 2, 4, 1, 0, 5]
bogoSort(a)
print("Sorted array:")
for i in range(len(a)):
    print ("%d" %a[i]),

Output

Sorted array:
0
1
2
3
4
5

Time Complexity:

Worst Case: O(∞) (since this algorithm has no upper bound)
Average Case: O(n*n!)
Best Case: O(n)(when the array given is already sorted)

Auxiliary Space: O(1)
Please refer complete article on BogoSort or Permutation Sort for more details!
 


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Last Updated : 29 Mar, 2023
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