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BubbleSort.java
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87 lines (79 loc) · 1.86 KB
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package com.ywh.sorting;
/**
* 冒泡排序
* [排序] [稳定排序]
*
* @author ywh
* @since 13/11/2019
*/
public class BubbleSort {
/**
* @param arr
* @param i
* @param j
*/
private void swap(int[] arr, int i, int j) {
int tmp = arr[i];
arr[i] = arr[j];
arr[j] = tmp;
}
/**
* end: [n - 1, 0)
* i: [0, end)
*
* Time: O(n^2), Space: O(1)
*
* @param arr
*/
public void sort(int[] arr) {
for (int end = arr.length - 1; end > 0; end--) {
for (int i = 0; i < end; i++) {
if (arr[i] > arr[i + 1]) {
swap(arr, i, i + 1);
}
}
}
}
/**
* 提早返回
*
* Time: O(n^2), Space: O(1)
*
* @param arr
*/
public void sortEarlyReturn(int[] arr) {
for (int end = arr.length - 1; end > 0; end--) {
// 如果子循环中没有发生交换，表示排序已完成，直接返回
boolean swapped = false;
for (int i = 0; i < end; i++) {
if (arr[i] > arr[i + 1]) {
swap(arr, i, i + 1);
swapped = true;
}
}
if (!swapped) {
return;
}
}
}
/**
* 跳过非必要的位置
*
* Time: O(n^2), Space: O(1)
*
* @param arr
*/
public void sortSkip(int[] arr) {
for (int end = arr.length - 1; end > 0; ) {
// 记录最后一次发生交换的位置，下次子循环到达这个位置即可
int newEnd = 0;
for (int i = 0; i < end; i++) {
if (arr[i] > arr[i + 1]) {
swap(arr, i, i + 1);
newEnd = i;
}
}
end = newEnd;
}
}
}