Java排序算法——归并排序

import java.util.Arrays;

public class MergeSort {

public static int[] sort(int[] a, int left, int right) {
if (left >= right) {
return a;
}
int mid = (left + right) / 2;
sort(a, left, mid);
sort(a, mid + 1, right);
return merge(a, left, mid, right);
}

private static int[] merge(int[] a, int left, int mid, int right) {
int[] tmp = new int[right + 1];
int center = mid + 1;
int index = left; // 记录临时数组的下标
int temp = left;
// 从两个数组中选择最小的放入临时数组
while (left <= mid && center <= right) {
tmp[index++] = (a[left] <= a[center]) ? a[left++] : a[center++];
}
// 剩余部分放入临时数组
while (center <= right) {
tmp[index++] = a[center++];
}
while (left <= mid) {
tmp[index++] = a[left++];
}
// 将临时数组copy回原数组
for (int i = temp; i <= right; i++) {
a[i] = tmp[i];
}
return a;
}

public static void main(String[] args) {
int[] arr = new int[] { 14, 12, 15, 13, 11, 16 };
arr = sort(arr, 0, arr.length - 1);
System.out.println(Arrays.toString(arr));
}
}