Question

我正在尝试对双打数组进行合并排序，但是出现错误。我需要你们的帮助。

import java.util.Arrays;
class MergeSort {

public static void main(String args[]) {
    MergeSort ob = new MergeSort();
    double nums[] = { 1.1, 1.2, 1.3, 2.2, 1.4, 2.3, 1.5, 9.8, 7.3, 7.7, 5.2, 5.1, 9.9, 4.1, 4.3, 4.2 };
    System.out.println("Original Array:");
    System.out.println(Arrays.toString(nums));
    ob.sort(nums, 0, nums.length - 1);
    System.out.println("Sorted Array:");
    System.out.println(Arrays.toString(nums));
}

void merge(double nums[], int left, int m, int right) {
    int n1 = m - left + 1;
    int n2 = right - m;

    int Left_part_arra[] = new int[n1];
    int Right_part_arra[] = new int[n2];

    for (int i = 0; i < n1; ++i)
        Left_part_arra[i] = nums[left + i];
    for (int j = 0; j < n2; ++j)
        Right_part_arra[j] = nums[m + 1 + j];

    int i = 0, j = 0;

    int k = left;
    while (i < n1 && j < n2) {
        if (Left_part_arra[i] <= Right_part_arra[j]) {
            nums[k] = Left_part_arra[i];
            i++;
        } else {
            nums[k] = Right_part_arra[j];
            j++;
        }
        k++;
    }

    while (i < n1) {
        nums[k] = Left_part_arra[i];
        i++;
        k++;
    }

    while (j < n2) {
        nums[k] = Right_part_arra[j];
        j++;
        k++;
    }
}

void sort(double nums[], int left, int right) {
    if (left < right) {
        int m = (left + right) / 2;
        sort(nums, left, m);
        sort(nums, m + 1, right);
        merge(nums, left, m, right);
    }
}}

我正在使用eclipse进行编码，而在此部分上我得到了红色下划线，我只是加了** **来强调。我尝试对其进行强制转换，但小数位数变为0。

for (int i = 0; i < n1; ++i)
        Left_part_arra[i] = **nums[left + i];**
    for (int j = 0; j < n2; ++j)
        Right_part_arra[j] = **nums[m + 1 + j];**

提前谢谢！

Answer 1

将代码更改为：

double Left_part_arra[] = new double[n1];
double Right_part_arra[] = new double[n2];

for (int i = 0; i < n1; ++i)
    Left_part_arra[i] = nums[left + i];
for (int j = 0; j < n2; ++j)
    Right_part_arra[j] = nums[m + 1 + j];

这给出了输出：

Original Array:
[1.1, 1.2, 1.3, 2.2, 1.4, 2.3, 1.5, 9.8, 7.3, 7.7, 5.2, 5.1, 9.9, 4.1, 4.3, 4.2]
Sorted Array:
[1.1, 1.2, 1.3, 1.4, 1.5, 2.2, 2.3, 4.1, 4.2, 4.3, 5.1, 5.2, 7.3, 7.7, 9.8, 9.9]

附带说明：尝试遵守Java变量命名约定，变量的首字母应小写。类/接口的首字母大写，常量完全用大写。 https://www.oracle.com/technetwork/java/codeconventions-135099.html

Java-双精度数组上的MergeSort

1 个答案: