C语言实现哈夫曼编码_哈夫曼编码压缩文件c语言

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//
// 霍夫曼编码
//
 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
/**思路：用一个有序链表（从大到小）来保存节点，然后通过链表来构造霍夫曼树, 再由霍夫曼树得到霍夫曼编码**/
 
typedef struct huffman_tree_node{
    int weight;//权重
    char c;//字符 非叶子节点为0
    struct huffman_tree_node * nextHuffmanTreeNode;//链表下一个节点
    struct huffman_tree_node * leftHuffmanTreeNode;//左节点
    struct huffman_tree_node * rightHuffmanTreeNode;//右节点
}HuffmanTreeNode; //霍夫曼树节点
 
typedef struct huffman_code{
    char *s;//编码 如  010， 00， ....
    int len;//编码长度
    char c;//字符
}HuffmanCode; //霍夫曼编码（可以用来保存结果）
 
/**
 * 创建一个节点
 * @param c  字符
 * @param weight 权重
 * @return
 */
HuffmanTreeNode * createHuffmanTreeNode(char c, int weight){
    HuffmanTreeNode * node = (HuffmanTreeNode *)calloc(1, sizeof(HuffmanTreeNode));
    node->c = c;
    node->weight = weight;
    node->nextHuffmanTreeNode = NULL;
    node->leftHuffmanTreeNode = NULL;
    node->rightHuffmanTreeNode = NULL;
    return node;
}
 
/**
 * [insert 插入节点到有序链表中]
 * @param  h [头节点指针]
 * @param  s [要插入的节点]
 * @return   [头节点]
 */
static HuffmanTreeNode * insert(HuffmanTreeNode * h, HuffmanTreeNode * s){
    if(h == NULL){ //插入第一个节点时 没有头节点
        return s;//s作为头节点
    }
    if(s->weight > h->weight){
        s->nextHuffmanTreeNode = h; //s作为头节点
        return s;
    }
 
    HuffmanTreeNode * tempHuffmanTreeNode = h; //中间变量 用于遍历
    HuffmanTreeNode * preHuffmanTreeNode = tempHuffmanTreeNode;//中间变量的前一个节点
    while(tempHuffmanTreeNode != NULL){
        if(s->weight < tempHuffmanTreeNode->weight){ //要插入的节点的学号比当前节点小
            preHuffmanTreeNode = tempHuffmanTreeNode;
            tempHuffmanTreeNode = tempHuffmanTreeNode->nextHuffmanTreeNode;
            continue;
        }
        //插入到中间
        preHuffmanTreeNode->nextHuffmanTreeNode = s;
        s->nextHuffmanTreeNode = tempHuffmanTreeNode;
        break;
    }
    if(tempHuffmanTreeNode == NULL){ //插入的节点比已有的节点都小
        preHuffmanTreeNode->nextHuffmanTreeNode = s;
    }
    return h;
}
 
/**
 * 移除最后一个节点（最小的那个） 并返回
 * @param node
 * @return
 */
HuffmanTreeNode * removeLastHuffmanTreeNode(HuffmanTreeNode * h){
    HuffmanTreeNode * tempHuffmanTreeNode = h; //中间变量 用于遍历
    HuffmanTreeNode * preHuffmanTreeNode = tempHuffmanTreeNode;//中间变量的前一个节点
    while(tempHuffmanTreeNode->nextHuffmanTreeNode != NULL){
            preHuffmanTreeNode = tempHuffmanTreeNode;
            tempHuffmanTreeNode = tempHuffmanTreeNode->nextHuffmanTreeNode;
        }
        preHuffmanTreeNode->nextHuffmanTreeNode = NULL;
    return tempHuffmanTreeNode;
}
 
/**
 * 链表转霍夫曼树
 * @param head
 * @return
 */
HuffmanTreeNode * createTree(HuffmanTreeNode * head){
    if(head == NULL){
        return NULL;
    }
    while (1){
        //获取最小的两个节点
        HuffmanTreeNode * node1 = removeLastHuffmanTreeNode(head);
        if(node1 == head){ //只有一个节点了 完成
            return node1;
        }
        HuffmanTreeNode * node2 = removeLastHuffmanTreeNode(head);
        if(node2 == head){ //最后一个节点
            head = NULL; //头节点置为NULL
        }
        //创建一个新的节点
        HuffmanTreeNode * newNode = createHuffmanTreeNode(0, node1->weight+node2->weight);
        //设置左节点
        newNode->leftHuffmanTreeNode = node1->weight <= node2->weight ? node1 : node2;
        //设置右节点
        newNode->rightHuffmanTreeNode = node1->weight <= node2->weight ? node2 : node1;
        //新节点插入到链表中，再次循环 直到链表中只有一个节点
        head = insert(head, newNode);
    }
}
 
/**
 * 字符串拷贝
 * @param s
 * @param len
 * @param dest
 */
void str_copy(char *s,int len ,char *dest){
    for(int i = 0; i < len; i++){
        dest[i] = s[i];
    }
}
 
/**
 * 霍夫曼编码
 * @param node 节点
 * @param s 编码的字符串 如 001,00,01...
 * @param len 编码字符串的长度
 */
void showCode(HuffmanTreeNode * node, char *s, int len){
    if(node->c != 0){ //到叶子节点了
        //打印编码结果（或保存到结构体中）：
        printf("%c->%s\n", node->c, s);
        free(s);
        return;
    }
    //遍历左节点 编码增加一个0
    char * leftS = (char *)calloc(len+1, sizeof(char));
    str_copy(s, len, leftS);
    leftS[len] = '0';
    showCode(node->leftHuffmanTreeNode, leftS, len+1);
 
    //遍历右节点 编码增加一个1
    char * rightS = (char *)calloc(len+1, sizeof(char));
    str_copy(s, len, rightS);
    rightS[len] = '1';
    showCode(node->rightHuffmanTreeNode, rightS, len+1);
	
    free(s);
 
}
int main(){
    //创建节点
    HuffmanTreeNode * head = NULL;
    HuffmanTreeNode * node_a = createHuffmanTreeNode('A', 5);
    HuffmanTreeNode * node_b = createHuffmanTreeNode('B', 4);
    HuffmanTreeNode * node_c = createHuffmanTreeNode('C', 3);
    HuffmanTreeNode * node_d = createHuffmanTreeNode('D', 2);
    HuffmanTreeNode * node_e = createHuffmanTreeNode('E', 1);
    //插入到有序链表中
    head = insert(head,node_a);
    head = insert(head,node_b);
    head = insert(head,node_c);
    head = insert(head,node_d);
    head = insert(head,node_e);
    //转霍夫曼树
    HuffmanTreeNode *tree =  createTree(head);
    printf("huffman encode:\n");
    //获取编码
	char * s  = (char*)malloc(0);
    showCode(tree, s, 0);
 
}

Jetbrains全家桶1年46，售后保障稳定