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struct Node {
char symbol; // 字符
int frequency; // 频率
Node* left;
Node* right;
Node(char symbol, int frequency)
: symbol(symbol), frequency(frequency), left(nullptr), right(nullptr) {}
};
// 比较函数,用于优先队列
struct CompareNode {
bool operator()(Node* a, Node* b) {
return a->frequency > b->frequency; // 小顶堆
}
};
// 递归生成哈夫曼编码表
void encode(Node* root, string str, unordered_map<char, string>& huffmanCode) {
if (!root) return;
if (!root->left && !root->right) {
huffmanCode[root->symbol] = str;
}
encode(root->left, str + "0", huffmanCode);
encode(root->right, str + "1", huffmanCode);
}
// 构建哈夫曼树
Node* buildHuffmanTree(const unordered_map<char, int>& freqMap) {
priority_queue<Node*, vector<Node*>, CompareNode> pq;
for (auto& pair : freqMap) {
pq.push(new Node(pair.first, pair.second));
}
while (pq.size() > 1) {
Node* left = pq.top(); pq.pop();
Node* right = pq.top(); pq.pop();
Node* parent = new Node('\0', left->frequency + right->frequency);
parent->left = left;
parent->right = right;
pq.push(parent);
}
return pq.empty() ? nullptr : pq.top();
}
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