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1 | 1 | package com.mistray.merge; |
2 | 2 |
|
| 3 | +import java.util.Arrays; |
| 4 | + |
3 | 5 | /** |
4 | 6 | * @author MistRay |
5 | 7 | * @create 2018年11月20日 |
|
8 | 10 | public class MergeSort { |
9 | 11 |
|
10 | 12 | public static void main(String[] args) { |
| 13 | + int[] array = { 35, 24, 86, 12, 95, 58, 35, 42, 21, 73 }; |
| 14 | + sort(array, 0, array.length - 1); |
| 15 | + System.out.println(Arrays.toString(array)); |
| 16 | + } |
| 17 | + |
| 18 | + public static void sort(int[] array, int start, int end){ |
| 19 | + if (start >= end){ |
| 20 | + return; |
| 21 | + } |
11 | 22 |
|
| 23 | + int mid = (start + end) >> 1; |
| 24 | + // 递归实现归并排序 |
| 25 | + sort(array, start, mid); |
| 26 | + sort(array, mid + 1, end); |
| 27 | + mergerSort(array, start, mid, end); |
12 | 28 | } |
13 | 29 |
|
14 | | - public static void mergeSort(){ |
| 30 | + // 将两个有序序列归并为一个有序序列(二路归并) |
| 31 | + private static void mergerSort(int[] array, int start, int mid, int end) { |
| 32 | + int[] arr = new int[end + 1]; // 定义一个临时数组,用来存储排序后的结果 |
| 33 | + int low = start; // 临时数组的索引 |
| 34 | + int left = start; |
| 35 | + |
| 36 | + int center = mid + 1; |
| 37 | + // 取出最小值放入临时数组中 |
| 38 | + while (start <= mid && center <= end) { |
| 39 | + arr[low++] = array[start] > array[center] ? array[center++] : array[start++]; |
| 40 | + } |
| 41 | + |
| 42 | + // 若还有段序列不为空,则将其加入临时数组末尾 |
| 43 | + |
| 44 | + while (start <= mid) { |
| 45 | + arr[low++] = array[start++]; |
| 46 | + } |
| 47 | + while (center <= end) { |
| 48 | + arr[low++] = array[center++]; |
| 49 | + } |
15 | 50 |
|
| 51 | + // 将临时数组中的值copy到原数组中 |
| 52 | + for (int i = left; i <= end; i++) { |
| 53 | + array[i] = arr[i]; |
| 54 | + } |
16 | 55 | } |
17 | 56 | } |
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