归并排序法数组中的最后一个数字总是不能进入排序是怎么回事

Question

代码如下

public void mergeSort(int f[], int l, int u) {
        // the algorithm of merge sorting
        if (l + 1 < u) {
            int mid = (l + u) / 2;
            mergeSort(f, l, mid);
            mergeSort(f, mid, u);
            merge(f, l, mid, u);
        }
    }
public void merge(int arr[], int l, int m, int r) {
        // the algorithm of merging
        int[] temp = new int[r - l + 1];
        int i = 0, j = 0, k = 0;
        // declare variable for counting

        if (r - l == 1) {
            int min = Math.min(arr[l], arr[r]);
            int max = Math.max(arr[l], arr[r]);
            arr[l] = min;
            arr[r] = max;
        }
        // the situation that there are only two numbers

        else {
            while (l + i < m && m + j < r) {
                if (arr[l + i] < arr[m + j]) {
                    temp[k] = arr[l + i];
                    k += 1;
                    i += 1;
                } else {
                    temp[k] = arr[m + j];
                    k += 1;
                    j += 1;
                }
            }
            while (l + i < m) {
                temp[k] = arr[l + i];
                k += 1;
                i += 1;
            }
            while (m + j < r) {
                temp[k] = arr[m + j];
                k += 1;
                j += 1;
            }
            for (int n = 0; n < temp.length - 1; n++) {
                arr[l + n] = temp[n];
            }
        }
    }

Answer 1

我测试了下，可以正常排序的，mergeSort(a, 0, a.length);你是这样调用的吗