归并排序

代码：

public class Code04_MergeSort {
public static int[] arr = {3,5,8,6,1,2,9,7,4,0};

public static void merge(int L, int mid, int R) {
    int[] temp = new int[R-L+1];    //辅助数组
    System.out.println(R + " " + L + " " + mid);
    int p1 = L, p2 = mid+1, idx = 0;
    while (p1 <= mid && p2 <= R) {
        if (arr[p1] <= arr[p2]) {
            temp[idx++] = arr[p1++];
        } else {
            temp[idx++] = arr[p2++];
        }
    }
    while (p1 <= mid) {
        System.out.println(idx);
        temp[idx++] = arr[p1++];
    }
    while (p2 <= R) {
        temp[idx++] = arr[p2++];
    }
    for (int i = 0; i < temp.length; i++) {
        arr[L + i] = temp[i];
    }
}
public static void mergeSort(int L, int R) {
    if (L >= R) {
        return;
    }
    int mid = (L+R)/2;
    mergeSort(L, mid);
    mergeSort(mid+1, R);
    merge(L, mid, R);
}
public static void main(String[] args) {
    System.out.println(arr);
    mergeSort(0, 9);
    for (int i = 0; i < arr.length; i++) {
        System.out.print(arr[i]);
    }
}
}