如何释放从vec中移除的对象的内存？

#include <iostream>
#include <vector>

int main() {
    std::vector<int> vec = {1, 2, 3, 4, 5};

    // 移除一些元素
    vec.erase(vec.begin() + 2);

    // 尝试减少容量以匹配大小
    vec.shrink_to_fit();

    std::cout << "Size: " << vec.size() << ", Capacity: " << vec.capacity() << std::endl;

    return 0;
}

#include <iostream>
#include <vector>

int main() {
    std::vector<int> vec = {1, 2, 3, 4, 5};

    // 移除一些元素
    vec.erase(vec.begin() + 2);

    // 使用 swap 技巧释放内存
    std::vector<int>().swap(vec);

    std::cout << "Size: " << vec.size() << ", Capacity: " << vec.capacity() << std::endl;

    return 0;
}

#include <iostream>
#include <vector>

class MyClass {
public:
    MyClass(int value) : data(new int(value)) {}
    ~MyClass() { delete data; }
private:
    int* data;
};

int main() {
    std::vector<MyClass*> vec;
    for (int i = 0; i < 5; ++i) {
        vec.push_back(new MyClass(i));
    }

    // 移除一些元素并释放内存
    for (auto it = vec.begin(); it != vec.end(); ) {
        if ((*it)->data == new int(2)) {
            delete *it;
            it = vec.erase(it);
        } else {
            ++it;
        }
    }

    // 释放剩余元素的内存
    for (auto ptr : vec) {
        delete ptr;
    }
    vec.clear();

    return 0;
}