哈夫曼编译码器c++

以下是一个C++实现的哈夫曼编译码器的示例代码：

#include <iostream>
#include <queue>
#include <unordered_map>
using namespace std;

// 哈夫曼树节点
struct Node {
    char data;
    int freq;
    Node* left;
    Node* right;

    Node(char data, int freq) {
        this->data = data;
        this->freq = freq;
        left = right = nullptr;
    }
};

// 用于比较节点频度的函数对象
struct Compare {
    bool operator()(Node* left, Node* right) {
        return left->freq > right->freq;
    }
};

// 构建哈夫曼树
Node* buildHuffmanTree(const unordered_map<char, int>& freqMap) {
    priority_queue<Node*, vector<Node*>, Compare> pq;

    // 将每个字符的频度作为节点加入优先队列
    for (const auto& pair : freqMap) {
        pq.push(new Node(pair.first, pair.second));
    }

    // 从优先队列中取出两个频度最小的节点，合并为一个新节点，直到只剩下一个节点
    while (pq.size() > 1) {
        Node* left = pq.top();
        pq.pop();
        Node* right = pq.top();
        pq.pop();

        Node* newNode = new Node('$', left->freq + right->freq);
        newNode->left = left;
        newNode->right = right;

        pq.push(newNode);
    }

    return pq.top();
}

// 递归构建哈夫曼编码表
void buildHuffmanCodes(Node* root, string code, unordered_map<char, string>& codes) {
    if (root == nullptr) {
        return;
    }

    if (root->data != '$') {
        codes[root->data] = code;
    }

    buildHuffmanCodes(root->left, code + "0", codes);
    buildHuffmanCodes(root->right, code + "1", codes);
}

// 哈夫曼编码
string encode(const string& text, const unordered_map<char, string>& codes) {
    string encodedText = "";
    for (char c : text) {
        encodedText += codes.at(c);
    }
    return encodedText;
}

// 哈夫曼译码
string decode(const string& encodedText, Node* root) {
    string decodedText = "";
    Node* curr = root;
    for (char bit : encodedText) {
        if (bit == '0') {
            curr = curr->left;
        } else {
            curr = curr->right;
        }

        if (curr->left == nullptr && curr->right == nullptr) {
            decodedText += curr->data;
            curr = root;
        }
    }
    return decodedText;
}

// 打印哈夫曼树
void printHuffmanTree(Node* root) {
    if (root == nullptr) {
        return;
    }

    cout << root->data << " - " << root->freq << endl;

    printHuffmanTree(root->left);
    printHuffmanTree(root->right);
}

int main() {
    string text = "hello world";

    // 统计字符频度
    unordered_map<char, int> freqMap;
    for (char c : text) {
        freqMap[c]++;
    }

    // 构建哈夫曼树
    Node* root = buildHuffmanTree(freqMap);

    // 构建哈夫曼编码表
    unordered_map<char, string> codes;
    buildHuffmanCodes(root, "", codes);

    // 哈夫曼编码
    string encodedText = encode(text, codes);
    cout << "Encoded text: " << encodedText << endl;

    // 哈夫曼译码
    string decodedText = decode(encodedText, root);
    cout << "Decoded text: " << decodedText << endl;

    // 打印哈夫曼树
    cout << "Huffman tree:" << endl;
    printHuffmanTree(root);

    return 0;
}