Course information
B2.4.3 · Sorting

Bubble sort

Python · step by step

Bubble sort

Watch the list change while following the actual Python execution.

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Python implementation

The highlight marks the next line to execute. Values show the state before that line.

def bubble_sort(items):    for end in range(len(items) - 1, 0, -1):        swapped = False        for j in range(end):            if items[j] > items[j + 1]:                items[j], items[j + 1] = items[j + 1], items[j]                swapped = True        if not swapped:            break    return items

The suffix beyond end is sorted. An early-exit flag gives O(n) best-case time; average and worst cases are O(n²). This in-place implementation uses O(1) auxiliary space.

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