public class MergeSortMain {public static void main(String[] args) {int[] arr = {5, 4, 6, 2, 3, 7, 9, 1, 8};sort(arr);print(arr);}static void sort(int[] arr) {sort(arr, 0, arr.length - 1);}/*** @param arr        数组* @param leftBound  左边界* @param rightBound 右边界*/static void sort(int[] arr, int leftBound, int rightBound) {if (leftBound == rightBound) {return;}// 获取右指针位置int rightPoint = leftBound + (rightBound - leftBound) / 2;// 左半部分排序sort(arr, leftBound, rightPoint);// 右半部分排序sort(arr, rightPoint + 1, rightBound);// 合并merge(arr, leftBound, rightPoint + 1, rightBound);}/*** @param arr        数组* @param leftPoint  左指针* @param rightPoint 右指针* @param rightBound 右边界*/static void merge(int[] arr, int leftPoint, int rightPoint, int rightBound) {// 创建一个临时数组int[] temp = new int[rightBound - leftPoint + 1];int mid = rightPoint - 1;int i = leftPoint;int j = rightPoint;// 临时数组指针位置int k = 0;// 这样子的循环条件出现, 比如left arr都小于right arr时, left指针移动完成跳出循环, right arr并将剩余数据插入临时数组while (i <= mid && j <= rightBound) {// 判断左边小于右边, 则放入临时数组if (arr[i] < arr[j]) {temp[k] = arr[i];k++;i++;} else {temp[k] = arr[j];k++;j++;}}while (i <= mid) {// 左边数组指针未移动完时temp[k] = arr[i];k++;i++;}while (j <= rightBound) {// 右边数组指针未移动完时temp[k] = arr[j];k++;j++;}for (int l = 0; l < temp.length; l++) {arr[leftPoint + l] = temp[l];}}static void print(int[] arr) {for (int i : arr) {System.out.print(i + " ");}System.out.println(" ");}
}