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Comment by maxk42 | Hacker News Reader

Because I have a need to optimize:

    // Given array a[1], ..., a[n]
    for i = 1 to n - 1:
        swapped = false
        for j = i + 1 to n:
                if a[i] > a[j]:
                    swapped = true
                    swap(a[i], a[j])
                if swapped == false:
                    break

This should reduce time complexity to O( (n - 1)^2 ) and stop sorting after the remainder of the array is sorted and tested one time.

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> This should reduce time complexity to O( (n - 1)^2 )

O((n-1)^2) = O(n^2).

I see where you're going, but your implementation broke the sort.

As for time complexity, it changes from ϴ(n²) to O(n²). Alternatively, you can drop the O-notation and calculate precisely so as to include constant factor speedups, though your algorithm may end up slower in the worst case.

it doesnt work though

        def swap(lst, a, b):
            tmp = lst[a]
            lst[a] = lst[b]
            lst[b] = tmp

        def optimized_sort(numbers):
            i = 0
            while i < len(numbers):
                swapped = False
                j = i + 1
                while  j < len(numbers):
                    if numbers[i] > numbers[j]:
                        swapped = True
                        swap(numbers, i, j)
                    if swapped == False:
                        break
                    j +=1 
                i+=1
            return numbers

        numbers  = [1, 4,7,3,7,12,55,3,11,2,9,88,8]
        optimized_sort([*numbers]) => [1, 4, 2, 7, 7, 12, 3, 3, 8, 9, 55, 11, 88]

removing the break gets you the correct order: [1, 2, 3, 3, 4, 7, 7, 8, 9, 11, 12, 55, 88]

Original code would be correct, if not for a few spaces - probably a typo.

This is why I like me some curly braces.

(Whitespace dependent languages suck when it comes to passing around code snippets - it's just the honest truth)

It was just an indentation typo. Swap check should be one level higher.

That would be decent sort which returns a slighly sorted output.

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