Comb Sort - Python

Comb Sort is an improvement over Bubble Sort that solves its main problem - small values near the end slowing down the sorting. It works by comparing elements far apart using a gap, which keeps reducing until it becomes 1. This allows faster movement of small elements toward the beginning and large elements toward the end.

How Comb Sort Works

1. Initialize the gap: Start with a large gap (usually len(arr) / 1.3), where 1.3 is the shrink factor found experimentally.
2. Compare and swap: Compare elements that are gap positions apart and swap if they’re out of order.
3. Shrink the gap: Reduce the gap by dividing it by 1.3 each pass until it becomes 1.
4. Final pass: When the gap is 1, the algorithm behaves like Bubble Sort to finish sorting.

Python Implementation

def combSort(arr):
    n = len(arr)
    gap = n
    swapped = True
    
    def getNextGap(gap):
        gap = int((gap * 10) / 13)
        return 1 if gap < 1 else gap
    
    while gap != 1 or swapped:
        gap = getNextGap(gap)
        swapped = False

        for i in range(0, n - gap):
            if arr[i] > arr[i + gap]:
                arr[i], arr[i + gap] = arr[i + gap], arr[i]
                swapped = True

arr = [8, 4, 1, 3, -44, 23, -6, 28, 0]
combSort(arr)

print(*arr)

-44 -6 0 1 3 4 8 23 28

Explanation:

• getNextGap(gap): Shrinks the gap by 1.3 and ensures it doesn’t go below 1.
• combSort(arr): Sorts array using gradually reducing gaps.
• while gap != 1 or swapped: Continues until array is sorted (gap = 1 and no swaps).
• if arr[i] > arr[i + gap]: Swaps out-of-order elements at gap distance.
• combSort(arr) & print(*arr): Sorts and prints the final sorted array.

Related Articles:

• Counting Sort - Python
• Merge Sort in Python