Add problem5 implementation and update CMakeLists and main.cpp

CMakeLists.txt

@@ -11,4 +11,6 @@ add_executable(data_structure_homework main.cpp
         problem3.cpp
         problem3.h
         problem4.cpp
-        problem4.h)
+        problem4.h
+        problem5.cpp
+        problem5.h)

main.cpp

@@ -5,6 +5,7 @@
 #include "problem2.h"
 #include "problem3.h"
 #include "problem4.h"
+#include "problem5.h"
 
 int main() {
     problem_1();
@@ -14,4 +15,6 @@ int main() {
     problem_3();
     std::cout << "------------------------" << std::endl;
     problem_4();
+    std::cout << "------------------------" << std::endl;
+    problem_5();
 }

problem5.cpp

@@ -0,0 +1,86 @@
+//
+// Created by grtsinry43 on 5/8/25.
+//
+
+#include "problem5.h"
+
+#include <iostream>
+#include <queue>
+#include <unordered_map>
+#include <vector>
+
+// 定义哈夫曼树节点
+struct HuffmanNode {
+    char character;
+    int frequency;
+    HuffmanNode *left;
+    HuffmanNode *right;
+
+    HuffmanNode(char ch, int freq) : character(ch), frequency(freq), left(nullptr), right(nullptr) {}
+};
+
+// 比较器，用于优先队列
+struct Compare {
+    bool operator()(HuffmanNode *a, HuffmanNode *b) {
+        return a->frequency > b->frequency;
+    }
+};
+
+// 构建哈夫曼树
+HuffmanNode* buildHuffmanTree(const std::unordered_map<char, int> &frequencyTable) {
+    std::priority_queue<HuffmanNode*, std::vector<HuffmanNode*>, Compare> pq;
+
+    // 将每个字符和频率插入优先队列
+    for (const auto &entry : frequencyTable) {
+        pq.push(new HuffmanNode(entry.first, entry.second));
+    }
+
+    // 构建哈夫曼树
+    while (pq.size() > 1) {
+        HuffmanNode *left = pq.top(); pq.pop();
+        HuffmanNode *right = pq.top(); pq.pop();
+
+        HuffmanNode *merged = new HuffmanNode('\0', left->frequency + right->frequency);
+        merged->left = left;
+        merged->right = right;
+
+        pq.push(merged);
+    }
+
+    return pq.top();
+}
+
+// 生成哈夫曼编码
+void generateHuffmanCodes(HuffmanNode *root, const std::string &code, std::unordered_map<char, std::string> &huffmanCodes) {
+    if (!root) return;
+
+    if (!root->left && !root->right) {
+        huffmanCodes[root->character] = code;
+    }
+
+    generateHuffmanCodes(root->left, code + "0", huffmanCodes);
+    generateHuffmanCodes(root->right, code + "1", huffmanCodes);
+}
+
+// 主函数
+int problem_5() {
+    // 示例字符频率表
+    std::unordered_map<char, int> frequencyTable = {
+        {'a', 5}, {'b', 9}, {'c', 12}, {'d', 13}, {'e', 16}, {'f', 45}
+    };
+
+    // 构建哈夫曼树
+    HuffmanNode *root = buildHuffmanTree(frequencyTable);
+
+    // 生成哈夫曼编码
+    std::unordered_map<char, std::string> huffmanCodes;
+    generateHuffmanCodes(root, "", huffmanCodes);
+
+    // 输出每个字符的哈夫曼编码
+    std::cout << "Huffman Codes:\n";
+    for (const auto &entry : huffmanCodes) {
+        std::cout << entry.first << ": " << entry.second << "\n";
+    }
+
+    return 0;
+}

problem5.h

@@ -0,0 +1,10 @@
+//
+// Created by grtsinry43 on 5/8/25.
+//
+
+#ifndef PROBLEM5_H
+#define PROBLEM5_H
+
+int problem_5();
+
+#endif //PROBLEM5_H