c语言实现哈夫曼编码

要实现哈夫曼编码，需要以下步骤：

1. 统计字符出现的频率
2. 构建哈夫曼树
3. 遍历哈夫曼树，给不同的字符赋予不同的编码
4. 将编码后的字符写入文件中

下面是一个简单的 C 语言实现：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>#define MAX_TREE_HT 100// 节点结构体
struct MinHeapNode {char data; // 字符unsigned freq; // 频率struct MinHeapNode *left, *right; // 左右子节点
};// 哈夫曼树结构体
struct MinHeap {unsigned size; // 大小unsigned capacity; // 容量struct MinHeapNode** array; // 数组
};// 创建节点
struct MinHeapNode* newNode(char data, unsigned freq) {struct MinHeapNode* temp = (struct MinHeapNode*) malloc(sizeof(struct MinHeapNode));temp->left = temp->right = NULL;temp->data = data;temp->freq = freq;return temp;
}// 创建一个大小为 capacity 的空的 MinHeap
struct MinHeap* createMinHeap(unsigned capacity) {struct MinHeap* minHeap = (struct MinHeap*) malloc(sizeof(struct MinHeap));minHeap->size = 0; // 初始化大小为 0minHeap->capacity = capacity;minHeap->array = (struct MinHeapNode**)malloc(minHeap->capacity * sizeof(struct MinHeapNode));return minHeap;
}// 交换 *a 和 *b 的值
void swapMinHeapNode(struct MinHeapNode** a, struct MinHeapNode** b) {struct MinHeapNode* temp = *a;*a = *b;*b = temp;
}// 维护最小堆的特性
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);}
}// 检查大小为 1 的最小堆
int isSizeOne(struct MinHeap* minHeap) {return (minHeap->size == 1);
}// 从 MinHeap 中取出最小的节点 (最小堆的根)
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;
}// 插入新的节点到 MinHeap 中
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;
}// 判断当前节点是否是叶子节点
int isLeaf(struct MinHeapNode* root) {return !(root->left) && !(root->right);
}// 创建并构建哈夫曼树
struct MinHeapNode* buildHuffmanTree(char data[], int freq[], int size) {struct MinHeapNode *left, *right, *top;// 创建一个最小堆，并初始化大小struct MinHeap* minHeap = createMinHeap(size);for (int i = 0; i < size; ++i)minHeap->array[i] = newNode(data[i], freq[i]);minHeap->size