哈夫曼编码译码c语言

下面是一个简单的哈夫曼编码和译码的 C 语言实现示例：

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

#define MAX_TREE_HT 100

// 哈夫曼树节点结构体
struct MinHeapNode {
    char data;
    unsigned freq;
    struct MinHeapNode *left, *right;
};

// 哈夫曼编码结构体
struct HuffmanCode {
    char data;
    char *code;
};

// 哈夫曼编码树结构体
struct MinHeap {
    unsigned size;
    unsigned capacity;
    struct MinHeapNode **array;
};

// 创建新的哈夫曼树节点
struct MinHeapNode *newNode(char data, unsigned freq) {
    struct MinHeapNode *node = (struct MinHeapNode *)malloc(sizeof(struct MinHeapNode));
    node->left = node->right = NULL;
    node->data = data;
    node->freq = freq;
    return node;
}

// 创建新的哈夫曼编码树
struct MinHeap *createMinHeap(unsigned capacity) {
    struct MinHeap *minHeap = (struct MinHeap *)malloc(sizeof(struct MinHeap));
    minHeap->size = 0;
    minHeap->capacity = capacity;
    minHeap->array = (struct MinHeapNode **)malloc(minHeap->capacity * sizeof(struct MinHeapNode *));
    return minHeap;
}

// 交换哈夫曼树节点
void swapMinHeapNode(struct MinHeapNode **a, struct MinHeapNode **b) {
    struct MinHeapNode *t = *a;
    *a = *b;
    *b = t;
}

// 维护最小堆的性质
void minHeapify(struct MinHeap *minHeap, int idx) {
    int smallest = idx;
    int left = 2 * idx + 1;
    int right = 2 * idx + 2;
    if (left < minHeap->size && minHeap->array[left]->freq < minHeap->array[smallest]->freq) {
        smallest = left;
    }
    if (right < minHeap->size && minHeap->array[right]->freq < minHeap->array[smallest]->freq) {
        smallest = right;
    }
    if (smallest != idx) {
        swapMinHeapNode(&minHeap->array[smallest], &minHeap->array[idx]);
        minHeapify(minHeap, smallest);
    }
}

// 判断堆是否为一元素堆
int isSizeOne(struct MinHeap *minHeap) {
    return (minHeap->size == 1);
}

// 获取最小频率的哈夫曼树节点
struct MinHeapNode *extractMin(struct MinHeap *minHeap) {
    struct MinHeapNode *temp = minHeap->array[0];
    minHeap->array[0] = minHeap->array[minHeap->size - 1];
    --minHeap->size;
    minHeapify(minHeap, 0);
    return temp;
}

// 插入新的哈夫曼树节点
void insertMinHeap(struct MinHeap *minHeap, struct MinHeapNode *minHeapNode) {
    ++minHeap->size;
    int i = minHeap->size - 1;
    while (i && minHeapNode->freq < minHeap->array[(i - 1) / 2]->freq) {
        minHeap->array[i] = minHeap->array[(i - 1) / 2];
        i = (i - 1) / 2;
    }
    minHeap->array[i] = minHeapNode;
}

// 判断是否为叶节点
int isLeaf(struct MinHeapNode *root) {
    return !(root->left) && !(root->right);
}

// 创建哈夫曼编码树
struct MinHeapNode *buildMinHeap(int *freq, char *data, int size) {
    struct MinHeapNode *left, *right, *top;
    struct MinHeap *minHeap = createMinHeap(size);
    for (int i = 0; i < size; ++i) {
        minHeap->array[i] = newNode(data[i], freq[i]);
    }
    minHeap->size = size;
    while (!isSizeOne(minHeap)) {
        left = extractMin(minHeap);
        right = extractMin(minHeap);
        top = newNode('$', left->freq + right->freq);
        top->left = left;
        top->right = right;
        insertMinHeap(minHeap, top);
    }
    return extractMin(minHeap);
}

// 生成哈夫曼编码
void generateHuffmanCodes(struct MinHeapNode *root, char *code, int top, struct HuffmanCode *huffmanCodes) {
    if (root->left) {
        code[top] = '0';
        generateHuffmanCodes(root->left, code, top + 1, huffmanCodes);
    }
    if (root->right) {
        code[top] = '1';
        generateHuffmanCodes(root->right, code, top + 1, huffmanCodes);
    }
    if (isLeaf(root)) {
        huffmanCodes[root->data].code = (char *)malloc((top + 1) * sizeof(char));
        strcpy(huffmanCodes[root->data].code, code);
        huffmanCodes[root->data].data = root->data;
    }
}

// 哈夫曼编码函数
void huffmanEncode(char *data, int *freq, int size) {
    struct MinHeapNode *root = buildMinHeap(freq, data, size);
    char code[MAX_TREE_HT], dataArr[size];
    struct HuffmanCode *huffmanCodes = (struct HuffmanCode *)malloc(size * sizeof(struct HuffmanCode));
    generateHuffmanCodes(root, code, 0, huffmanCodes);
    printf("Huffman Codes:\n");
    for (int i = 0; i < size; ++i) {
        printf("%c: %s\n", huffmanCodes[data[i]].data, huffmanCodes[data[i]].code);
    }
}

// 哈夫曼解码函数
void huffmanDecode(struct MinHeapNode *root, char *code, int index) {
    if (!root) {
        return;
    }
    if (isLeaf(root)) {
        printf("%c", root->data);
        return;
    }
    ++index;
    if (code[index] == '0') {
        huffmanDecode(root->left, code, index);
    } else {
        huffmanDecode(root->right, code, index);
    }
}

int main() {
    char data[] = {'a', 'b', 'c', 'd', 'e', 'f'};
    int freq[] = {5, 9, 12, 13, 16, 45};
    int size = sizeof(data) / sizeof(data[0]);
    huffmanEncode(data, freq, size);
    struct MinHeapNode *root = buildMinHeap(freq, data, size);
    printf("\nDecoded data: ");
    char code[] = "11000101111110100011101001";
    int index = -1;
    while (index < (int)strlen(code) - 2) {
        huffmanDecode(root, code, index);
    }
    return 0;
}

这个示例中，包含了创建哈夫曼树节点、创建哈夫曼编码树、交换哈夫曼树节点、维护最小堆的性质、获取最小频率的哈夫曼树节点、插入新的哈夫曼树节点、判断是否为叶节点、生成哈夫曼编码、哈夫曼编码函数、哈夫曼解码函数等多个函数，可以根据自己的需求进行修改和完善。