c语言写哈夫曼树编码

C语言可以用数组和结构体来实现哈夫曼树编码。以下是一个简单的示例代码：

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

#define MAX_TREE_HT 100

typedef struct MinHeapNode {
    char data;
    unsigned freq;
    struct MinHeapNode *left, *right;
} MinHeapNode;

typedef struct MinHeap {
    unsigned size;
    unsigned capacity;
    MinHeapNode **array;
} MinHeap;

typedef struct HuffmanNode {
    char data;
    char *code;
    struct HuffmanNode *next;
} HuffmanNode;

typedef struct HuffmanTable {
    HuffmanNode *head;
} HuffmanTable;

MinHeapNode *newNode(char data, unsigned freq) {
    MinHeapNode *node = (MinHeapNode *) malloc(sizeof(MinHeapNode));
    node->left = node->right = NULL;
    node->data = data;
    node->freq = freq;
    return node;
}

MinHeap *createMinHeap(unsigned capacity) {
    MinHeap *minHeap = (MinHeap *) malloc(sizeof(MinHeap));
    minHeap->size = 0;
    minHeap->capacity = capacity;
    minHeap->array = (MinHeapNode **) malloc(minHeap->capacity * sizeof(MinHeapNode *));
    return minHeap;
}

void swapMinHeapNode(MinHeapNode **a, MinHeapNode **b) {
    MinHeapNode *t = *a;
    *a = *b;
    *b = t;
}

void minHeapify(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);
    }
}

int isSizeOne(MinHeap *minHeap) {
    return (minHeap->size == 1);
}

MinHeapNode *extractMin(MinHeap *minHeap) {
    MinHeapNode *temp = minHeap->array[0];
    minHeap->array[0] = minHeap->array[minHeap->size - 1];
    --minHeap->size;
    minHeapify(minHeap, 0);
    return temp;
}

void insertMinHeap(MinHeap *minHeap, 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;
}

void buildMinHeap(MinHeap *minHeap) {
    int n = minHeap->size - 1;
    int i;
    for (i = (n - 1) / 2; i >= 0; --i)
        minHeapify(minHeap, i);
}

void printArr(int arr[], int n) {
    int i;
    for (i = 0; i < n; ++i)
        printf("%d", arr[i]);
    printf("\n");
}

int isLeaf(MinHeapNode *root) {
    return !(root->left) && !(root->right);
}

MinHeap *createAndBuildMinHeap(char data[], int freq[], int size) {
    MinHeap *minHeap = createMinHeap(size);
    for (int i = 0; i < size; ++i)
        minHeap->array[i] = newNode(data[i], freq[i]);
    minHeap->size = size;
    buildMinHeap(minHeap);
    return minHeap;
}

MinHeapNode *buildHuffmanTree(char data[], int freq[], int size) {
    MinHeapNode *left, *right, *top;
    MinHeap *minHeap = createAndBuildMinHeap(data, freq, 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);
}

void printCodes(MinHeapNode *root, int arr[], int top, HuffmanTable *table) {
    if (root->left) {
        arr[top] = 0;
        printCodes(root->left, arr, top + 1, table);
    }
    if (root->right) {
        arr[top] = 1;
        printCodes(root->right, arr, top + 1, table);
    }
    if (isLeaf(root)) {
        HuffmanNode *node = (HuffmanNode *) malloc(sizeof(HuffmanNode));
        node->data = root->data;
        node->code = (char *) malloc((top + 1) * sizeof(char));
        for (int i = 0; i < top; ++i)
            node->code[i] = arr[i] + '0';
        node->code[top] = '\0';
        node->next = table->head;
        table->head = node;
    }
}

void HuffmanCoding(char data[], int freq[], int size, HuffmanTable *table) {
    MinHeapNode *root = buildHuffmanTree(data, freq, size);
    int arr[MAX_TREE_HT], top = 0;
    printCodes(root, arr, top, table);
}

void printTable(HuffmanTable *table) {
    HuffmanNode *node = table->head;
    while (node) {
        printf("%c: %s\n", node->data, node->code);
        node = node->next;
    }
}

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]);
    HuffmanTable *table = (HuffmanTable *) malloc(sizeof(HuffmanTable));
    table->head = NULL;
    HuffmanCoding(data, freq, size, table);
    printTable(table);
    return 0;
}