Bubble Sort

O(n²) average and worst case. O(1) space. Stable sort.

Speed

Size

Unsorted

Comparing

Swapping

Sorted

Implementation

void BubbleSort(int[] arr)
{
    for (var i = arr.Length - 1; i > 0; i--)
    {
        var swapped = false;

        for (var j = 0; j < i; j++)
        {
            if (arr[j] > arr[j + 1])
            {
                (arr[j], arr[j + 1]) = (arr[j + 1], arr[j]);
                swapped = true;
            }
        }

        if (!swapped) break;
    }
}

def bubble_sort(arr: list[int]) -> None:
    for i in range(len(arr) - 1, 0, -1):
        swapped = False

        for j in range(i):
            if arr[j] > arr[j + 1]:
                arr[j], arr[j + 1] = arr[j + 1], arr[j]
                swapped = True

        if not swapped:
            break

function bubbleSort(arr: number[]): void {
  for (let i = arr.length - 1; i > 0; i--) {
    let swapped = false;

    for (let j = 0; j < i; j++) {
      if (arr[j] > arr[j + 1]) {
        [arr[j], arr[j + 1]] = [arr[j + 1], arr[j]];
        swapped = true;
      }
    }

    if (!swapped) break;
  }
}

How it works

Algorithm

Repeatedly walks through the array, compares adjacent elements, and swaps them if they are in the wrong order. Each pass bubbles the largest unsorted element to its final position.

When to use

Teaching tool. In practice, almost never. It is the simplest sorting algorithm to understand and implement, which makes it good for learning, but it is too slow for real workloads.