哈夫曼树的构造c语言代码

下面是一个简单的哈夫曼树构造的 C 语言代码示例：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAX_NODE_NUM 1000
#define MAX_CODE_LEN 100

typedef struct TreeNode {
    char data;
    int weight;
    struct TreeNode *left;
    struct TreeNode *right;
} TreeNode;

void huffman_encoding(TreeNode *root, char *code, int len) {
    static char code_table[MAX_NODE_NUM][MAX_CODE_LEN];
    if (root->left == NULL && root->right == NULL) {
        strncpy(code_table[root->data], code, len);
        code_table[root->data][len] = '\0';
        return;
    }
    code[len] = '0';
    huffman_encoding(root->left, code, len+1);
    code[len] = '1';
    huffman_encoding(root->right, code, len+1);
}

void huffman_tree(TreeNode **root, char *str) {
    int count[256] = {0};
    for (int i=0; i<strlen(str); i++) {
        count[(int)str[i]]++;
    }
    struct {
        int weight;
        TreeNode *node;
    } nodes[MAX_NODE_NUM];
    int node_num = 0;
    for (int i=0; i<256; i++) {
        if (count[i] > 0) {
            nodes[node_num].node = (TreeNode *)malloc(sizeof(TreeNode));
            nodes[node_num].node->data = i;
            nodes[node_num].node->weight = count[i];
            nodes[node_num].node->left = NULL;
            nodes[node_num].node->right = NULL;
            nodes[node_num].weight = count[i];
            node_num++;
        }
    }
    while (node_num > 1) {
        int min1 = 0, min2 = 1;
        if (nodes[min1].weight > nodes[min2].weight) {
            int tmp = min1;
            min1 = min2;
            min2 = tmp;
        }
        for (int i=2; i<node_num; i++) {
            if (nodes[i].weight < nodes[min1].weight) {
                min2 = min1;
                min1 = i;
            } else if (nodes[i].weight < nodes[min2].weight) {
                min2 = i;
            }
        }
        TreeNode *new_node = (TreeNode *)malloc(sizeof(TreeNode));
        new_node->data = '\0';
        new_node->weight = nodes[min1].weight + nodes[min2].weight;
        new_node->left = nodes[min1].node;
        new_node->right = nodes[min2].node;
        nodes[min1].node = new_node;
        nodes[min1].weight = new_node->weight;
        nodes[min2] = nodes[node_num-1];
        node_num--;
    }
    *root = nodes[0].node;
}

int main() {
    char str[] = "hello world";
    TreeNode *root;
    huffman_tree(&root, str);
    char code[MAX_CODE_LEN];
    huffman_encoding(root, code, 0);
    for (int i=0; i<256; i++) {
        if (strlen(code_table[i]) > 0) {
            printf("%c: %s\n", (char)i, code_table[i]);
        }
    }
    return 0;
}

该代码将一个字符串进行哈夫曼树编码，并输出每个字符的编码结果。