JAVA归并排序代码

JAVA归并排序的代码如下：

public class MergeSort {
    public static void main(String[] args) {
        int[] arr = { 38, 27, 43, 3, 9, 82, 10 };
        System.out.println("排序前:");
        printArr(arr);
        mergeSort(arr, 0, arr.length - 1);
        System.out.println("排序后:");
        printArr(arr);
    }

    public static void mergeSort(int[] arr, int left, int right) {
        if (left < right) {
            int mid = (left + right) / 2;
            mergeSort(arr, left, mid);
            mergeSort(arr, mid + 1, right);
            merge(arr, left, mid, right);
        }
    }

    public static void merge(int[] arr, int left, int mid, int right) {
        int[] temp = new int[right - left + 1];
        int i = left;
        int j = mid + 1;
        int k = 0;

        while (i <= mid && j <= right) {
            if (arr[i] < arr[j]) {
                temp[k++] = arr[i++];
            } else {
                temp[k++] = arr[j++];
            }
        }

        while (i <= mid) {
            temp[k++] = arr[i++];
        }

        while (j <= right) {
            temp[k++] = arr[j++];
        }

        for (int p = 0; p < temp.length; p++) {
            arr[left + p] = temp[p];
        }
    }

    public static void printArr(int[] arr) {
        for (int i : arr) {
            System.out.print(i + " ");
        }
        System.out.println();
    }
}

归并排序是一种典型的分治算法。它将待排序的元素分为两个大小大致相等的子集合，然后递归地排序两个子集合，最后将已经排好序的子集合合并成为最终的排好序的序列。