也不包含map头文件-Go服务器开发

如果不使用 <map> 头文件，你可以自己实现一个简单的哈希表来存储字符和对应的编码。下面是一个示例代码：

#include <iostream>
#include <cstring>

struct HNode {
    char data;
    int frequency;
    HNode* left;
    HNode* right;

    HNode(char c, int freq) : data(c), frequency(freq), left(nullptr), right(nullptr) {}
};

// 简单的哈希表结构
struct HashMap {
    static const int SIZE = 128; // 假设字符范围在 ASCII 0-127

    struct Entry {
        char key;
        std::string value;
        Entry* next;

        Entry(char k, const std::string& v) : key(k), value(v), next(nullptr) {}
    };

    Entry* table[SIZE];

    HashMap() {
        memset(table, 0, sizeof(table));
    }

    void put(char key, const std::string& value) {
        int index = key % SIZE;

        if (table[index] == nullptr) {
            table[index] = new Entry(key, value);
            return;
        }

        Entry* entry = table[index];
        while (entry->next != nullptr)
            entry = entry->next;

        entry->next = new Entry(key, value);
    }

    std::string get(char key) {
        int index = key % SIZE;

        Entry* entry = table[index];
        while (entry != nullptr && entry->key != key)
            entry = entry->next;

        return (entry != nullptr) ? entry->value : "";
    }
};

void EncodeHelper(HNode* node, std::string code, HashMap& encoding) {
	if (node == nullptr) {
		return;
	}

	if (node->left == nullptr && node->right == nullptr) { // 叶子节点
		encoding.put(node->data, code);
		return;
	}

    EncodeHelper(node->left, code + "0", encoding);
    EncodeHelper(node->right, code + "1", encoding);
}

HashMap BuildEncoding(HNode* root) {
	HashMap encoding;

	if (root == nullptr)
	    return encoding;

	EncodeHelper(root, "", encoding);

	return encoding;
}

void Encode(char* s, char* d) {
    // 统计字符频率
	int frequencies[128] = { 0 };
	for (int i = 0; s[i] != '\0'; ++i) {
        frequencies[s[i]]++;
    }

    // 构建 Huffman 树
	std::vector<HNode*> nodes;
	for (int i = 0; i < 128; ++i) {
	    if (frequencies[i] > 0) {
	        nodes.push_back(new HNode(static_cast<char>(i), frequencies[i]));
	    }
	}
	
	while (nodes.size() > 1) {
	    std::sort(nodes.begin(), nodes.end(), [](HNode* a, HNode* b) {
	        return a->frequency > b->frequency;
	    });

	    HNode* left = nodes.back();
	    nodes.pop_back();

	    HNode* right = nodes.back();
	    nodes.pop_back();

	    HNode* parent = new HNode('\0', left->frequency + right->frequency);
	    parent->left = left;
        parent->right = right;

        nodes.push_back(parent);
    }

    // 构建编码表
    HashMap encoding = BuildEncoding(nodes[0]);

    // 编码输入字符串
	std::string encodedStr;
	for (int i = 0; s[i] != '\0'; ++i) {
        encodedStr += encoding.get(s[i]);
    }

	strcpy(d, encodedStr.c_str());
}

int main() {
	char str[100];
	char encoded[100];

	std::cout << "Enter a string to encode: ";
	std::cin >> str;

	Encode(str, encoded);

	std::cout << "Encoded string: " << encoded << std::endl;

	return 0;
}

这段代码使用自定义的哈希表结构 HashMap 来存储字符和对应的编码。同样，注意这只是一个简化的示例，实际的编码函数可能需要更多的错误处理和边界条件检查。

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