用c＋＋写一份代码，要求用哈夫曼树进行编码（从终端读入字符集大小n以及n个字符和n个权值，建立赫夫曼树）

在C++中，你可以使用STL（标准模板库）中的`priority_queue`来构建一个最小堆，然后通过递归的方式生成赫夫曼树。这里是一个简单的示例，用于读取字符集大小、字符和权值，构建赫夫曼树，然后生成编码：

#include <iostream>
#include <queue>
#include <unordered_map>

struct Node {
    char data;
    int weight;
    int freq;
    Node* left = nullptr;
    Node* right = nullptr;

    // 添加左右孩子节点和更新频率
    void add_child(Node* child) {
        if (child->freq > 0)
            freq += child->freq;
        if (left == nullptr)
            left = child;
        else if (right == nullptr)
            right = child;
        child->parent = this;
    }
};

Node* build_huffman_tree(int n, std::vector<char>& chars, std::vector<int>& weights) {
    std::priority_queue<std::pair<int, Node*>, std::vector<std::pair<int, Node*>>, std::greater<int>> huffman_heap;
    
    for (int i = 0; i < n; ++i) {
        Node node(chars[i], weights[i], 1);
        huffman_heap.push({weights[i], &node});
    }

    while (huffman_heap.size() > 1) {
        Node* left = huffman_heap.top().second;
        huffman_heap.pop();
        Node* right = huffman_heap.top().second;
        huffman_heap.pop();

        Node* newNode = new Node;
        newNode->add_child(left);
        newNode->add_child(right);

        huffman_heap.push({left->freq + right->freq, newNode});
    }

    return huffman_heap.top().second;
}

std::string encode(const std::string& message, const Node* root) {
    std::string encoded;
    for (char c : message) {
        Node* current = root;
        while (true) {
            encoded += (current->data == c ? '0' : '1');
            if (current->left && current->left->data == c)
                current = current->left;
            else if (current->right && current->right->data == c)
                current = current->right;
            else
                break;
        }
    }
    return encoded;
}

int main() {
    int n;
    std::cout << "Enter the number of characters: ";
    std::cin >> n;

    std::vector<char> chars(n);
    std::vector<int> weights(n);
    std::cout << "Enter the characters and their corresponding weights: ";
    for (int i = 0; i < n; ++i) {
        std::cin >> chars[i] >> weights[i];
    }

    Node* huffTree = build_huffman_tree(n, chars, weights);
    std::string input;
    std::getline(std::cin, input);
    std::string encoded = encode(input, huffTree);

    std::cout << "Encoded message: " << encoded << "\n";
    delete huffTree;

    return 0;
}

这个程序首先读取字符集大小和权重，然后构建赫夫曼树。接着，用户输入一段文本，程序将其编码。注意，由于Huffman编码是动态生成的，所以实际的编码过程依赖于输入字符集的具体情况。