归并排序（Java语言）

?视频讲解地址：【手把手带你写十大排序】6.归并排序（Java语言）_哔哩哔哩_bilibili

代码：

public class MergeSort {

    public void sortFunction(int[] array) {
        int[] tempArray = new int[array.length];
        mergeSortFunction(array, tempArray, 0, array.length - 1);
    }

    public void mergeSortFunction(int[] array, int[] tempArray, int begin, int end) {
        if (begin < end) {
            int mid = begin + ((end - begin) >> 1);
            mergeSortFunction(array, tempArray, begin, mid);
            mergeSortFunction(array, tempArray, mid + 1, end);
            merge(array, tempArray, begin, mid, end);
        }
    }

    public void merge(int[] array, int[] tempArray, int begin, int mid, int end) {
        int leftPos = begin;
        int rightPos = mid + 1;
        int tempArrayPos = begin;
        while (leftPos <= mid && rightPos <= end) {
            if (array[leftPos] < array[rightPos]) {
                tempArray[tempArrayPos++] = array[leftPos++];
            } else {
                tempArray[tempArrayPos++] = array[rightPos++];
            }
        }
        while (leftPos <= mid) {
            tempArray[tempArrayPos++] = array[leftPos++];
        }
        while (rightPos <= end) {
            tempArray[tempArrayPos++] = array[rightPos++];
        }
        for (int i = begin; i <= end; i++) {
            array[i] = tempArray[i];
        }
    }
}