请用c++代码实现基于两阶段归并排序的集合运算，包括交、并操作。要求有模拟缓冲区设置、模拟磁盘元组数据分块存储、模拟磁盘I/O输入输出、模拟缓冲区运算四个基本功能。元组模拟用整数型数据即可。请详细注释，需能在VS2019编译运行

#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>

using namespace std;

const int buffer_size = 5; // 缓冲区大小
const int block_size = 10; // 磁盘块大小

// 缓冲区结构体
struct Buffer {
    int data[buffer_size];
    int size;
};

// 写入磁盘块
void write_block(int block_num, vector<int>& data) {
    ofstream fout(to_string(block_num));
    for (int i = 0; i < block_size; i++) {
        if (i < data.size()) {
            fout << data[i] << endl;
        } else {
            fout << -1 << endl; // 块剩余部分用-1填充
        }
    }
    fout.close();
}

// 读取磁盘块
vector<int> read_block(int block_num) {
    vector<int> data;
    ifstream fin(to_string(block_num));
    int num;
    while (fin >> num) {
        if (num != -1) {
            data.push_back(num);
        } else {
            break;
        }
    }
    fin.close();
    return data;
}

// 内存中的排序
void sort_buffer(Buffer& buffer) {
    sort(buffer.data, buffer.data + buffer.size);
}

// 归并两个有序数组
vector<int> merge(vector<int>& a, vector<int>& b) {
    vector<int> res;
    int i = 0, j = 0;
    while (i < a.size() && j < b.size()) {
        if (a[i] == b[j]) {
            res.push_back(a[i]);
            i++;
            j++;
        } else if (a[i] < b[j]) {
            res.push_back(a[i]);
            i++;
        } else {
            res.push_back(b[j]);
            j++;
        }
    }
    while (i < a.size()) {
        res.push_back(a[i]);
        i++;
    }
    while (j < b.size()) {
        res.push_back(b[j]);
        j++;
    }
    return res;
}

// 从缓冲区读取数据
vector<int> read_from_buffer(Buffer& buffer, int num) {
    vector<int> res;
    int i = 0;
    while (i < buffer.size && res.size() < num) {
        res.push_back(buffer.data[i]);
        i++;
    }
    buffer.size -= res.size();
    for (int j = i; j < buffer.size; j++) {
        buffer.data[j-i] = buffer.data[j];
    }
    for (int j = buffer.size; j < buffer_size; j++) {
        buffer.data[j] = -1;
    }
    return res;
}

// 向缓冲区写入数据
void write_to_buffer(Buffer& buffer, vector<int>& data) {
    int i = 0;
    while (i < data.size() && buffer.size < buffer_size) {
        buffer.data[buffer.size] = data[i];
        buffer.size++;
        i++;
    }
}

// 交操作
vector<int> intersect(vector<int>& a, vector<int>& b) {
    vector<int> res;
    int i = 0, j = 0;
    while (i < a.size() && j < b.size()) {
        if (a[i] == b[j]) {
            res.push_back(a[i]);
            i++;
            j++;
        } else if (a[i] < b[j]) {
            i++;
        } else {
            j++;
        }
    }
    return res;
}

// 并操作
vector<int> merge(vector<int>& a, vector<int>& b) {
    vector<int> res;
    int i = 0, j = 0;
    while (i < a.size() && j < b.size()) {
        if (a[i] == b[j]) {
            res.push_back(a[i]);
            i++;
            j++;
        } else if (a[i] < b[j]) {
            res.push_back(a[i]);
            i++;
        } else {
            res.push_back(b[j]);
            j++;
        }
    }
    while (i < a.size()) {
        res.push_back(a[i]);
        i++;
    }
    while (j < b.size()) {
        res.push_back(b[j]);
        j++;
    }
    return res;
}

// 两阶段归并排序
vector<int> two_phase_merge_sort(vector<vector<int>>& data) {
    // 第一阶段：内存排序
    for (auto& d : data) {
        sort(d.begin(), d.end());
    }
    // 第二阶段：归并
    while (data.size() > 1) {
        vector<vector<int>> tmp;
        for (int i = 0; i < data.size(); i += 2) {
            if (i == data.size() - 1) {
                tmp.push_back(data[i]);
            } else {
                tmp.push_back(merge(data[i], data[i+1]));
            }
        }
        data = tmp;
    }
    return data[0];
}

// 交集运算
void intersect_operation(vector<int>& a, vector<int>& b) {
    vector<vector<int>> blocks_a, blocks_b;
    int block_num_a = 0, block_num_b = 0;
    // 将a、b分块存储到磁盘
    for (int i = 0; i < a.size(); i += block_size) {
        vector<int> block_data_a = read_from_buffer(a_buffer, block_size);
        write_to_buffer(a_buffer, block_data_a);
        blocks_a.push_back(block_data_a);
        write_block(block_num_a, block_data_a);
        block_num_a++;
    }
    for (int i = 0; i < b.size(); i += block_size) {
        vector<int> block_data_b = read_from_buffer(b_buffer, block_size);
        write_to_buffer(b_buffer, block_data_b);
        blocks_b.push_back(block_data_b);
        write_block(block_num_b, block_data_b);
        block_num_b++;
    }
    // 对磁盘上的数据进行排序和归并
    vector<vector<int>> sorted_blocks_a, sorted_blocks_b;
    for (int i = 0; i < block_num_a; i++) {
        sorted_blocks_a.push_back(read_block(i));
    }
    for (int i = 0; i < block_num_b; i++) {
        sorted_blocks_b.push_back(read_block(i));
    }
    vector<int> sorted_a = two_phase_merge_sort(sorted_blocks_a);
    vector<int> sorted_b = two_phase_merge_sort(sorted_blocks_b);
    // 对有序数组进行交集操作
    vector<int> res = intersect(sorted_a, sorted_b);
    // 输出结果
    cout << "交集运算结果为：" << endl;
    for (auto& num : res) {
        cout << num << " ";
    }
    cout << endl;
}

// 并集运算
void merge_operation(vector<int>& a, vector<int>& b) {
    vector<vector<int>> blocks_a, blocks_b;
    int block_num_a = 0, block_num_b = 0;
    // 将a、b分块存储到磁盘
    for (int i = 0; i < a.size(); i += block_size) {
        vector<int> block_data_a = read_from_buffer(a_buffer, block_size);
        write_to_buffer(a_buffer, block_data_a);
        blocks_a.push_back(block_data_a);
        write_block(block_num_a, block_data_a);
        block_num_a++;
    }
    for (int i = 0; i < b.size(); i += block_size) {
        vector<int> block_data_b = read_from_buffer(b_buffer, block_size);
        write_to_buffer(b_buffer, block_data_b);
        blocks_b.push_back(block_data_b);
        write_block(block_num_b, block_data_b);
        block_num_b++;
    }
    // 对磁盘上的数据进行排序和归并
    vector<vector<int>> sorted_blocks_a, sorted_blocks_b;
    for (int i = 0; i < block_num_a; i++) {
        sorted_blocks_a.push_back(read_block(i));
    }
    for (int i = 0; i < block_num_b; i++) {
        sorted_blocks_b.push_back(read_block(i));
    }
    vector<int> sorted_a = two_phase_merge_sort(sorted_blocks_a);
    vector<int> sorted_b = two_phase_merge_sort(sorted_blocks_b);
    // 对有序数组进行并集操作
    vector<int> res = merge(sorted_a, sorted_b);
    // 输出结果
    cout << "并集运算结果为：" << endl;
    for (auto& num : res) {
        cout << num << " ";
    }
    cout << endl;
}

int main() {
    // 初始化缓冲区
    Buffer a_buffer = {{-1, -1, -1, -1, -1}, 0};
    Buffer b_buffer = {{-1, -1, -1, -1, -1}, 0};
    // 初始化两个集合
    vector<int> a = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15};
    vector<int> b = {5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19};
    // 进行交集运算
    intersect_operation(a, b);
    // 进行并集运算
    merge_operation(a, b);
    return 0;
}