设计一个基于哈夫曼编码算法的通信编译码过程

Question

基本要求：          初始化一个26个英文字母（小写）对应的权值序列（存储在文本文件中）。从文件读出数据，建立哈夫曼树。模拟一个通信出错的过程：比如说发送的是11011001010，收到的是11111001010，接收方要能够检查出来。模拟通信无差错的过程，即接收到的序列没有错误，则译码。  
概要设计（参考）  1. 读取文本文件，获取每个字母对应的权值 2. 建立哈夫曼树3. 哈夫曼编码 4. 哈夫曼译码（有错，无错）  详细设计：

Answer 1

以下是一个基于哈夫曼编码算法的通信编译码过程的大致设计：

```cpp
#include <iostream>
#include <fstream>
#include <unordered_map>
#include <queue>

struct Node {
    char letter;
    int frequency;
    Node* left;
    Node* right;
};

struct Compare {
    bool operator()(Node* a, Node* b) {
        return a->frequency > b->frequency;
    }
};

std::unordered_map<char, std::string> huffmanCodes;

void generateCodes(Node* root, std::string code) {
    if (root->left != nullptr) {
        generateCodes(root->left, code + "0");
    }
    if (root->right != nullptr) {
        generateCodes(root->right, code + "1");
    }
    if (root->letter != '\0') {
        huffmanCodes[root->letter] = code;
    }
}

Node* buildHuffmanTree(std::unordered_map<char, int>& frequencyTable) {
    std::priority_queue<Node*, std::vector<Node*>, Compare> minHeap;
    
    for (auto& pair : frequencyTable) {
        Node* newNode = new Node;
        newNode->letter = pair.first;
        newNode->frequency = pair.second;
        newNode->left = nullptr;
        newNode->right = nullptr;
        minHeap.push(newNode);
    }

    while (minHeap.size() > 1) {
        Node* left = minHeap.top();
        minHeap.pop();

        Node* right = minHeap.top();
        minHeap.pop();

        Node* merge = new Node;
        merge->frequency = left->frequency + right->frequency;
        merge->left = left;
        merge->right = right;

        minHeap.push(merge);
    }

    return minHeap.top();
}

void encode(const std::string& data) {
    std::string encodedData;
    for (char c : data) {
        encodedData += huffmanCodes[c];
    }
    std::cout << "Encoded data: " << encodedData << std::endl;
}

void decode(const std::string& data, Node* root) {
    std::string decodedData;
    Node* current = root;
    for (char bit : data) {
        if (bit == '0') {
            current = current->left;
        } else {
            current = current->right;
        }
        if (current->letter != '\0') {
            decodedData += current->letter;
            current = root;
        }
    }
    std::cout << "Decoded data: " << decodedData << std::endl;
}

int main() {
    std::ifstream file("frequency.txt");
    std::unordered_map<char, int> frequencyTable;

    char letter;
    int frequency;

    while (file >> letter >> frequency) {
        frequencyTable[letter] = frequency;
    }
    file.close();

    Node* root = buildHuffmanTree(frequencyTable);

    generateCodes(root, "");

    std::string originalData = "hello";
    encode(originalData);

    std::string receivedData = "11011001010";
    decode(receivedData, root);
    
    std::string receivedDataWithError = "11111001010";
    decode(receivedDataWithError, root);

    return 0;
}

这段代码实现了哈夫曼编码和译码过程，包括读取文本文件获取权值，建立哈夫曼树，哈夫曼编码，以及模拟收发数据并进行译码的过程。这里没有加入错误检测和纠错的具体实现，具体可根据需求进一步扩展。

```