qfedu-cpp-level/day4/homework/h6_2.cpp

// 自定义ArrayList类，实现线性列表（类似数组）结构的数据元素操作。操作方法：
//     1. add(int) 添加int整型的数据元素
//     2. remove(int) 删除数据元素
//     3. int get(int index) 获取指定位置的元素
//     4. void print() 打印列表中所有元素
//     5. int size() 返回列表的当前大小
//     6. void sort(bool reversed = false) 元素排序，reversed为true时，表示从大小到小，反之，表示从小到到。

#include <iostream>

using namespace std;

class ArrayList
{
private:
    int *elements; // 存储元素的数组
    int capacity;  // 数组的容量
    int count;     // 当前元素的数量
public:
    ArrayList() : capacity(10), elements(new int[capacity]), count(0) {}
    ~ArrayList()
    {
        delete[] elements;
    }

public:
    void add(int value);
    void remove(int index);
    int get(int index);
    void print();
    int size();
    void sort(bool reversed = false);
};

void ArrayList::add(int value)
{
    if (count == capacity)
    {
        // 如果数组已满，扩容为原来的两倍
        int newCapacity = capacity * 2;
        int *newElements = new int[newCapacity];
        for (int i = 0; i < count; i++)
        {
            newElements[i] == elements[i];
        }
        delete[] elements;
        elements = newElements;
        capacity = newCapacity;
    }
    elements[count] = value;
    count++;
}

void ArrayList::remove(int index)
{
    if (index >= 0 && index < count)
    {
        for (int i = index; i < count - 1; i++)
        {
            // index 后面的元素全部前移一位
            elements[i] = elements[i + 1];
        }
        count--;
    }
}

int ArrayList::get(int index)
{
    if (index >= 0 && index < count)
        return elements[index];
    return -1; // 返回无效值，表示未找到内容
}

void ArrayList::print()
{
    for (int i = 0; i < count; i++)
        cout << elements[i] << " ";
    cout << endl;
}

int ArrayList::size()
{
    return count;
}

void ArrayList::sort(bool reversed)
{
    for (int i = 0; i < count - 1; i++)
    {
        for (int j = 0; j < count - i - 1; j++)
        {
            if (reversed) // 等价于 reversed == true
            {
                if (elements[j] < elements[j + 1])
                {
                    int tmp = elements[j];
                    elements[j] = elements[j + 1];
                    elements[j + 1] = tmp;
                }
            }
            else
            {
                if (elements[j] > elements[j + 1])
                {
                    int tmp = elements[j];
                    elements[j] = elements[j + 1];
                    elements[j + 1] = tmp;
                }
            }
        }
    }
}

int main()
{
    ArrayList list;

    list.add(5);
    list.add(8);
    list.add(7);
    list.add(2);
    list.add(1);

    cout << "原始列表: ";
    list.print();
    cout << endl;

    cout << "列表大小为: " << list.size() << endl;

    cout << "删除第二位的元素后显示为: ";
    list.remove(2);
    list.print();
    cout << endl;

    cout << "此时第二位的元素为: " << list.get(2) << endl;

    cout << "从大到小排序后列表为: ";
    list.sort(true);
    list.print();
    cout << endl;

    cout << "从小到大排序后列表为: ";
    list.sort();
    list.print();
    cout << endl;

    return 0;
}