归并排序是使用递归的方法把一个数组分割成最小的单元，然后在合并成一个数组。
在数据量较大时归并排序的效率比简单排序的效率要高，逻辑也不太复杂。下面是完整的归并排序方法类
package com.brave.guib; /*** 归并排序完整版* * 归并排序是将要排序的数组进行分割，直到分割为最小的单元，* 即一个数组中只有一个元素，然后将有序数组重组成一个数组* @author 小二郎，上学堂**/ public class Guib {private int[] arr;//数组private int num;//计数public Guib(int max) {arr = new int[max];num = 0;}//插入方法public void insert(int val){arr[num++] = val;}//循环打印public void display(){for (int i = 0; i < arr.length; i++) {System.out.print(arr[i] + "\n");}}//排序方法public void mergeSort(){int[] workSpace = new int[num];recMergeSort(workSpace, 0, num-1);}//递归调用方法private void recMergeSort(int[] workSpace,int lowerB,int upperB){if(lowerB == upperB) return;else{int mid = (lowerB + upperB)/2;recMergeSort(workSpace, lowerB, mid);recMergeSort(workSpace, mid + 1, upperB);merge(workSpace, lowerB, mid+1, upperB);}}//合并两个有序数组的方法private void merge(int[] workSpace,int lower,int upper,int upperB){int j = 0;int lowerB = lower;int mid = upper - 1;int n = upperB - lowerB + 1;while(lower <=mid && upper <= upperB){workSpace[j++] = (arr[lower] < arr[upper]?arr[lower++]:arr[upper++]);}while(lower <= mid)workSpace[j++] = arr[lower++];while(upper <= upperB)workSpace[j++] = arr[upper++];for ( j = 0; j < n; j++) {arr[lowerB + j] = workSpace[j];}}}
希望能够通过这些代码帮助大家更好的理解归并排序
