diff --git a/day4/homework/h6_2.cpp b/day4/homework/h6_2.cpp
index 9324bed..71204c0 100644
--- a/day4/homework/h6_2.cpp
+++ b/day4/homework/h6_2.cpp
@@ -1,3 +1,11 @@
+// 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;
@@ -5,5 +13,136 @@ using namespace std;
 class ArrayList
 {
 private:
-    int
-};
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+    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;
+}
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