#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef int Elemtype;
typedef int Status;
//赫夫曼树结点定义
typedef struct HuffmanNode {
Elemtype weight; //用来记录结点的权重
Elemtype id; //用来唯一标识结点
struct HuffmanNode *lchild;
struct HuffmanNode *rchild;
}*HuffmanTree;
//构建一颗赫夫曼树//
HuffmanTree CreateHuffmanTree(int a[],int n) {
//返回指向根结点的指针
//数组a代表每个结点的权重,n代表叶子结点个数
int i, j;
HuffmanTree *temp, T;
//动态分配n个结点的内存空间,temp为指向这些地址空间的头指针
temp = (HuffmanTree *)malloc(n * sizeof(HuffmanNode));
//将数组a中的权值分配给每个结点
for (i = 0; i < n; i++) {
temp[i] = (HuffmanTree)malloc(sizeof(HuffmanNode));
temp[i]->weight = a[i];
temp[i]->id = i;
temp[i]->lchild = temp[i]->rchild = NULL;
}
//构建哈夫曼树
for (i = 0; i < n - 1; i++) {
//构建哈夫曼树需要n-1次合并
int little1 = -1, little2;//前者存放最小的数的下标,后者存放次小的
for (j = 0; j < n; j++) {
if (temp[j] != NULL && little1 == -1) {
little1 = j;
continue;
}
else if (temp[j] != NULL) {
little2 = j;
break;//找到了就可以跳出
}
}
//将权值最小的两个数给little1,2
for (j = little2; j < n; j++) {
if (temp[j] != NULL) {
if (temp[j]->weight < temp[little1]->weight) {
little2 = little1;
little1 = j; //将次小的给2,自己留更小的一个
}
else if (temp[j]->weight < temp[little2]->weight) {
little2 = j;
}
}
}
//构造结点
T = (HuffmanTree)malloc(sizeof(HuffmanNode));
T->weight = temp[little1]->weight + temp[little2]->weight;//权值为两结点相加
T->lchild = temp[little1];
T->rchild = temp[little2];
temp[little1] = T; //将构造的结点插入队列中
temp[little2] = NULL;//删去另外的两个结点
}
return T;
}
//用广义表的形式打印这棵树//
void printHuffmanTree(HuffmanTree T) {
if (T) {
printf("%d", T->weight);
if (T->lchild != NULL || T->rchild != NULL) {
//如果不是叶子结点则执行,如果是的话直接跳出
//有一个小森林就会有一对括号,即执行这一步
printf("(");
printHuffmanTree(T->lchild); //先打印左子树
printf(","); //左右子树中用逗号隔开
printHuffmanTree(T->rchild); //再打印右子树
printf(")");
}
}
}
//递归进行赫夫曼编码//
void HuffmanCode(HuffmanTree T, int depth,char str[]) {
static int code[100];//每次递归值都不会改变,但是一棵树遍历左右子树是值是会变的
static int i = 0;
if (T) {
if (T->lchild == NULL && T->rchild == NULL) {
//如果该结点是叶子结点的话
printf("%c的哈夫曼编码为:",str[T->id]);
i++;
for (int i = 0; i < depth; i++) {
printf("%d", code[i]);
}
printf("\n");
}
else {
//如果不是叶子结点就进行数值写入
//左子树写0,右子树写1,根结点写0
code[depth] = 0;
HuffmanCode(T->lchild, depth + 1,str);
code[depth] = 1; //此时同样深度的code发生了改变
HuffmanCode(T->rchild, depth + 1,str);
}
}
}
//赫夫曼解码//
void HuffmanDecode(HuffmanTree T, char ch[], char str[]) {
//ch为要解码的01串,str为解码后的字符串
int i, num[1000];//num用来存放01码
HuffmanTree temp = NULL;
//进行存放01码
for (i = 0; i < strlen(ch); i++) {
if (ch[i] == 48)
num[i] = 0;
else if (ch[i] == 49)
num[i] = 1;
}
//进行解码
if(T) {
i = 0;//用来记录01串长度
while (i < strlen(ch)) {
//当还没有解码完的时候
temp = T;
while (temp->lchild != NULL && temp->rchild != NULL) {
//当不是叶子结点的时候都要继续
if (num[i] == 0) {
temp = temp->lchild;//如果是0就走左边
}
else {
temp = temp->rchild;//如果是1就走右边
}
i++;
}
//退出的时候就找到了叶子结点,由temp指向
printf("%c", str[temp->id]);//输出对应的字符
}
}
}
int main() {
int a[53];
int n = 53;
char ch[1000];//用来接收01码
char str[53];//用来存放字母
for (int i = 65; i <= 90; i++) {
//大写字母从A-Z
str[i - 65] = i;
}
str[26] = 32; //空格的ASCII码
for (int i = 97; i <= 122; i++) {
//小写字母从a-z
str[26 + i - 96] = i;
}
for (int i = 0; i < 53; i++) {
//权重值从1-53
a[i] = i + 1;
}
HuffmanTree T;
T = (HuffmanTree)malloc(sizeof(HuffmanNode));
T = CreateHuffmanTree(a, n);
printf("(");
printHuffmanTree(T);
printf(")\n");
HuffmanCode(T, 0,str);
printf("请输入您要解码的01值:");
scanf("%s",ch);
printf("解码的结果是:\n");
HuffmanDecode(T, ch, str);
return 0;
}
【数据结构】哈夫曼编码树
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转载自blog.csdn.net/haohulala/article/details/95666966
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