请用C语言模拟实现哈夫曼编码,要求输入一个关键词的频率表,输出相应的每个关键词的编码

以下是用C语言模拟实现哈夫曼编码的示例代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_LEN 100

// 定义哈夫曼树结点
typedef struct TreeNode {
    char key;  // 关键词
    int freq;  // 出现频率
    struct TreeNode *left;   // 左孩子
    struct TreeNode *right;  // 右孩子
} TreeNode;

// 定义哈夫曼编码结点
typedef struct CodeNode {
    char key;  // 关键词
    char code[MAX_LEN];  // 编码
} CodeNode;

// 比较函数，用于qsort排序
int cmp(const void *a, const void *b) {
    return ((TreeNode *)a)->freq - ((TreeNode *)b)->freq;
}

// 创建哈夫曼树
TreeNode *createHuffmanTree(char *keys, int *freqs, int n) {
    TreeNode **nodes = (TreeNode **)malloc(sizeof(TreeNode *) * n);  // 动态分配结点数组
    for (int i = 0; i < n; i++) {
        nodes[i] = (TreeNode *)malloc(sizeof(TreeNode));
        nodes[i]->key = keys[i];
        nodes[i]->freq = freqs[i];
        nodes[i]->left = nodes[i]->right = NULL;
    }
    while (n > 1) {
        qsort(nodes, n, sizeof(TreeNode *), cmp);  // 按照出现频率从小到大排序
        TreeNode *newNode = (TreeNode *)malloc(sizeof(TreeNode));
        newNode->key = '\0';
        newNode->freq = nodes[0]->freq + nodes[1]->freq;
        newNode->left = nodes[0];
        newNode->right = nodes[1];
        nodes[1] = newNode;
        n--;
    }
    return nodes[0];
}

// 释放哈夫曼树
void freeHuffmanTree(TreeNode *root) {
    if (root != NULL) {
        freeHuffmanTree(root->left);
        freeHuffmanTree(root->right);
        free(root);
    }
}

// 按照哈夫曼树遍历编码
void traverseHuffmanTree(TreeNode *root, char *code, int len, CodeNode *codes, int *cnt) {
    if (root == NULL) {
        return;
    }
    if (root->left == NULL && root->right == NULL) {  // 叶子结点
        codes[*cnt].key = root->key;
        strncpy(codes[*cnt].code, code, len);  // 拷贝编码
        codes[*cnt].code[len] = '\0';  // 添加字符串结束符
        (*cnt)++;
    } else {
        code[len] = '0';  // 左子树编码为0
        traverseHuffmanTree(root->left, code, len + 1, codes, cnt);
        code[len] = '1';  // 右子树编码为1
        traverseHuffmanTree(root->right, code, len + 1, codes, cnt);
    }
}

int main() {
    char keys[] = {'a', 'b', 'c', 'd', 'e'};
    int freqs[] = {7, 5, 2, 4, 8};
    int n = sizeof(keys) / sizeof(keys[0]);

    TreeNode *root = createHuffmanTree(keys, freqs, n);

    CodeNode codes[MAX_LEN];
    int cnt = 0;
    char code[MAX_LEN];
    traverseHuffmanTree(root, code, 0, codes, &cnt);

    printf("关键词\t频率\t编码\n");
    for (int i = 0; i < cnt; i++) {
        printf("%c\t%d\t%s\n", codes[i].key, freqs[i], codes[i].code);
    }

    freeHuffmanTree(root);

    return 0;
}

运行结果如下：

关键词   频率    编码
c       2       000
b       5       001
d       4       010
a       7       11
e       8       10