> For the complete documentation index, see [llms.txt](https://liuyang89116.gitbook.io/my-leetcode-book/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://liuyang89116.gitbook.io/my-leetcode-book/basics_of_sorting/bubble_sort.md).

# Bubble Sort

## 思路

核心：**冒泡**，持续比较相邻元素，大的挪到后面，因此大的会逐步往后挪，故称之为冒泡。

![](/files/-Lpv9zUt00ycq71_IrYw)

## 复杂度分析

**Best**: $$\Omega (n)$$\
**Worst**: $$O(n^2)$$\
**Average**: $$\Theta(n^2)$$

```java
package bubbleSort;

public class BubbleSort {
    public static void main(String[] args) {
        int[] unsortedArr = new int[] { 6, 5, 3, 1, 8, 7, 2, 4 };
        bubbleSort(unsortedArr);
        System.out.println("After Sort: ");
        printArr(unsortedArr);
    }

    private static void bubbleSort(int[] arr) {
        int len = arr.length;
        for (int i = 0; i < len; i++) {
            printArr(arr);
            System.out.println();
            for (int j = 1; j < len - i; j++) {
                if (arr[j - 1] > arr[j]) {
                    swap(arr, j - 1, j);
                }
            }
        }
    }

    private static void swap(int[] arr, int i, int j) {
        int tmp = arr[i];
        arr[i] = arr[j];
        arr[j] = tmp;
    }

    private static void printArr(int[] arr) {
        for (Integer num : arr) {
            System.out.print(num + " ");
        }
    }
}
```