利用Python和C语言分别实现哈夫曼编码(Python 哈夫曼编码)

1.C语言实现

1.1代码说明

a 创建双向链表：

在创建哈夫曼树的过程中，需要不断对结点进行更改和删除，所以选用双向链表的结构更容易

'''C
#include <stdlib.h>
#include <stdio.h>
#include <windows.h>
 
 
//哈夫曼树结构体，数据域存储字符及其权重
typedef struct node
{
 char c;
 int weight;
 struct node *lchild, *rchild;
}Huffman, *Tree;
 
 
//双向链表结构体，数据域存储哈夫曼树结点
typedef struct list
{
 Tree root;
 struct list *pre;
 struct list *next;
}List, *pList;
 
 
//创建双向链表，返回头结点指针
pList creatList()
{
 pList head = (pList)malloc(sizeof(List));
 
 pList temp1 = head;
 pList temp2 = (pList)malloc(sizeof(List));
 temp1->pre = NULL;
 temp1->next = temp2;
 temp1->root = (Tree)malloc(sizeof(Huffman));
 temp1->root->c = 'a';
 temp1->root->weight = 22;
 temp1->root->lchild = NULL;
 temp1->root->rchild = NULL;
 
 
 temp2->pre = temp1;
 temp1 = temp2;
 temp2 = (pList)malloc(sizeof(List));
 temp1->next = temp2;
 temp1->root = (Tree)malloc(sizeof(Huffman));
 temp1->root->c = 'b';
 temp1->root->weight = 5;
 temp1->root->lchild = NULL;
 temp1->root->rchild = NULL;
 
 
 temp2->pre = temp1;
 temp1 = temp2;
 temp2 = (pList)malloc(sizeof(List));
 temp1->next = temp2;
 temp1->root = (Tree)malloc(sizeof(Huffman));
 temp1->root->c = 'c';
 temp1->root->weight = 38;
 temp1->root->lchild = NULL;
 temp1->root->rchild = NULL;
 
 temp2->pre = temp1;
 temp1 = temp2;
 temp2 = (pList)malloc(sizeof(List));
 temp1->next = temp2;
 temp1->root = (Tree)malloc(sizeof(Huffman));
 temp1->root->c = 'd';
 temp1->root->weight = 9;
 temp1->root->lchild = NULL;
 temp1->root->rchild = NULL;
 
 temp2->pre = temp1;
 temp1 = temp2;
 temp2 = (pList)malloc(sizeof(List));
 temp1->next = temp2;
 temp1->root = (Tree)malloc(sizeof(Huffman));
 temp1->root->c = 'e';
 temp1->root->weight = 44;
 temp1->root->lchild = NULL;
 temp1->root->rchild = NULL;
 
 temp2->pre = temp1;
 temp1 = temp2;
 temp2 = (pList)malloc(sizeof(List));
 temp1->next = temp2;
 temp1->root = (Tree)malloc(sizeof(Huffman));
 temp1->root->c = 'f';
 temp1->root->weight = 12;
 temp1->root->lchild = NULL;
 temp1->root->rchild = NULL;
 
 temp2->pre = temp1;
 temp1 = temp2;
 temp1->next = NULL;
 temp1->root = (Tree)malloc(sizeof(Huffman));
 temp1->root->c = 'g';
 temp1->root->weight = 65;
 temp1->root->lchild = NULL;
 temp1->root->rchild = NULL;
 
 return head;  
}

b创建栈结构：

解码过程需要用到两个栈，一个用来存放树结点，一个用来存放码0和1

'''C
#define STACK_INIT_SIZE 100//栈初始开辟空间大小
#define STACK_INCREMENT 10 //栈追加空间大小
 
//字符栈结构体，存放编码'0'和'1'
typedef struct {
 char *base;
 char *top;
 int size;
}charStack;
 
 
//栈初始化
charStack charStackInit()
{
 charStack s;
 s.base = (char *)malloc(sizeof(char)*STACK_INIT_SIZE);
 s.top = s.base;
 s.size = STACK_INIT_SIZE;
 return s;
}
 
//入栈
void charPush(charStack *s, char e)
{
 if(s->top - s->base >= s->size)
 {
  s->size += STACK_INCREMENT;
  s->base = realloc(s->base, sizeof(char)*s->size);
 }
 *s->top = e;
 s->top++;
}
 
//出栈
char charPop(charStack *s)
{
 if(s->top != s->base)
 {
  s->top--;
  return *s->top;
 }
 return -1;
}
 
//得到栈顶元素，但不出栈
char charGetTop(charStack *s)
{
 s->top--;
 char temp = *s->top;
 s->top++;
 return temp;
}
 
//栈结构体，存放哈夫曼树结点
typedef struct 
{
 Huffman *base;
 Huffman *top;
 int size;
}BiStack;
 
//栈初始化
BiStack stackInit()
{
 BiStack s;
 s.base = (Huffman *)malloc(sizeof(Huffman)*STACK_INIT_SIZE);
 s.top = s.base;
 s.size =STACK_INIT_SIZE;
 return s;
}
 
//入栈
void push(BiStack *s, Huffman e)
{
 if(s->top - s->base >= s->size)
 {
  s->size += STACK_INCREMENT;
  s->base = (Huffman *)realloc(s->base, sizeof(Huffman)*s->size);
 }
 *s->top = e;
 s->top++;
}
 
//出栈
Huffman pop(BiStack *s)
{
 Huffman temp;
 s->top--;
 temp = *s->top;
 return temp;
}
 
//得到栈顶元素，但不出栈
Huffman getTop(BiStack s)
{
 Huffman temp;
 s.top--;
 temp = *s.top;
 return temp;
}
 
char stack[7][10]; //记录a~g的编码
//遍历栈，得到字符c的编码
void traverseStack(charStack s, char c)
{
 int index = c - 'a'; 
 int i = 0;
 while(s.base != s.top)
 {
  stack[index][i] = *s.base;
  i++;
  s.base++;
 }
}

c 创建哈夫曼树：

'''C
//通过双向链表创建哈夫曼树，返回根结点指针
Tree creatHuffman(pList head)
{
 pList list1 = NULL;
 pList list2 = NULL;
 pList index = NULL;
 Tree root = NULL;
 while(head->next != NULL)//链表只剩一个结点时循环结束，此结点数据域即为哈夫曼树的根结点
 {
  list1 = head;
  list2 = head->next;
  index = list2->next;
  root = (Tree)malloc(sizeof(Huffman));
  while(index != NULL) //找到链表中权重最小的两个结点list1,list2
  {
if(list1->root->weight > index->root->weight || list2->root->weight > index->root->weight)
{
 if(list1->root->weight > list2->root->weight) list1 = index;
 else list2 = index;
}
index = index->next;
  }
  //list1和list2设为新结点的左右孩子
  if(list2->root->weight > list1->root->weight)
  {
root->lchild = list1->root;
root->rchild = list2->root;
  }
  else
  {
root->lchild = list2->root;
root->rchild = list1->root;
  }
  //新结点字符统一设为空格，权重设为list1与list2权重之和
  root->c = ' ';
  root->weight = list1->root->weight + list2->root->weight;
  //list1数据域替换成新结点，并删除list2
  list1->root = root;
  list2->pre->next = list2->next;
  if(list2->next != NULL)
list2->next->pre = list2->pre; 
 }
 return head->root;
}

d编码：

'''C
char stack[7][10]; //记录a~g的编码
//遍历栈，得到字符c的编码
void traverseStack(charStack s, char c)
{
 int index = c - 'a'; 
 int i = 0;
 while(s.base != s.top)
 {
  stack[index][i] = *s.base;
  i++;
  s.base++;
 }
}
 
 
//通过哈夫曼树编码
void encodeHuffman(Tree T)
{  
 BiStack bs = stackInit();
 charStack cs = charStackInit();
 Huffman root = *T;  
 Tree temp = NULL;
 push(&bs, root);//根结点入栈
 while(bs.top != bs.base)//栈空表示遍历结束
 {
  root = getTop(bs);
  temp = root.lchild; //先访问左孩子
  while(temp != NULL) //左孩子不为空
  {
//将结点左孩子设为空，代表已访问其左孩子
root.lchild = NULL;
pop(&bs);
push(&bs, root);
//左孩子入栈
root = *temp;
temp = root.lchild;
push(&bs, root);
//'0'入字符栈
charPush(&cs, '0');
  }
  temp = root.rchild;  //后访问右孩子  
  while(temp == NULL)  //右孩子为空，代表左右孩子均已访问，结点可以出栈 
  {
//结点出栈
root = pop(&bs);
//寻到叶子结点，可以得到结点中字符的编码
if(root.c != ' ')
 traverseStack(cs, root.c);
charPop(&cs); //字符栈出栈
if(bs.top == bs.base) break; //根结点出栈，遍历结束
//查看上一级结点是否访问完左右孩子  
root = getTop(bs);
temp = root.rchild;  
  }
  if(bs.top != bs.base)
  {
//将结点右孩子设为空，代表已访问其右孩子
root.rchild = NULL; 
pop(&bs);
push(&bs, root);
//右孩子入栈
root = *temp;
push(&bs, root);
//'1'入字符栈
charPush(&cs, '1');
  } 
 }
}

e解码：

'''C
char decode[100];//记录解码得到的字符串
//通过哈夫曼树解码
void decodeHuffman(Tree T, char *code)
{
 int cnt = 0;
 Tree root;
 while(*code != '\0')//01编码字符串读完，解码结束
 {
  root = T;
  while(root->lchild != NULL) //找到叶子结点
  {
if(*code != '\0')
{
 if(*code == '0')
  root = root->lchild;
 else
  root = root->rchild;
 code++;
}
else break;
  }
  decode[cnt] = root->c; //叶子结点存放的字符即为解码得到的字符
  cnt++;
 }
}

f主函数：

'''C
void main()
{
 pList pl = creatList();
 printf("字符的权重如下\n");
 for(pList l = pl; l->next != NULL; l = l->next)
  printf("字符%c的权重是 %d\n", l->root->c, l->root->weight);
 Tree T = creatHuffman(pl);
 encodeHuffman(T);
 printf("\n\n字符编码结果如下\n");
 for(int i = 0; i < 7; i++)
  printf("%c : %s\n", i+'a', stack[i]);
 char code[100];
 printf("\n\n请输入编码：\n");
 scanf("%s", code);
 printf("解码结果如下：\n");
 decodeHuffman(T, code);
 printf("%s\n", decode);
 printf("\n\n");
 system("date /T");
 system("TIME /T");
 system("pause");
 exit(0); 
}

1.2运行结果

2.Python实现

2.1代码说明

a创建哈夫曼树：

#coding=gbk
 
import datetime
import time
from pip._vendor.distlib.compat import raw_input
 
#哈夫曼树结点类
class Huffman:
 def __init__(self, c, weight):
  self.c = c
  self.weight = weight
  self.lchild = None
  self.rchild = None
 
 #创建结点左右孩子 
 def creat(self, lchild, rchild):
  self.lchild = lchild
  self.rchild = rchild
 
#创建列表  
def creatList():
 list = []
 list.append(Huffman('a', 22))
 list.append(Huffman('b', 5))
 list.append(Huffman('c', 38))
 list.append(Huffman('d', 9))
 list.append(Huffman('e', 44))
 list.append(Huffman('f', 12))
 list.append(Huffman('g', 65))
 return list
 
#通过列表创建哈夫曼树，返回树的根结点
def creatHuffman(list):
 while len(list) > 1:#列表只剩一个结点时循环结束，此结点即为哈夫曼树的根结点
  i = 0
  j = 1
  k = 2
  while k < len(list):  #找到列表中权重最小的两个结点list1,list2 
if list[i].weight > list[k].weight or list[j].weight > list[k].weight:
 if list[i].weight > list[j].weight:
  i = k
 else:
  j = k
k += 1 
  root = Huffman(' ', list[i].weight + list[j].weight) #新结点字符统一设为空格，权重设为list1与list2权重之和
  if list[i].weight < list[j].weight:#list1和list2设为新结点的左右孩子
root.creat(list[i], list[j])
  else:
root.creat(list[j], list[i])
  #list1数据域替换成新结点，并删除list2
  list[i] = root
  list.remove(list[j])
 return list[0]

b编码：

#通过哈夫曼树编码
def encodeHuffman(T):
 code = [[], [], [], [], [], [], []]
 #列表实现栈结构
 treeStack = []
 codeStack = []
 treeStack.append(T)
 while treeStack != []:  #栈空代表遍历结束
  root = treeStack[-1]
  temp = root.lchild
  while temp != None:
#将结点左孩子设为空，代表已访问其左孩子
root.lchild = None  
#左孩子入栈 
treeStack.append(temp)
root = temp
temp = root.lchild
#0入编码栈
codeStack.append(0)
  temp = root.rchild#后访问右孩子
  while temp == None:  #右孩子为空，代表左右孩子均已访问，结点可以出栈
root = treeStack.pop()  #结点出栈
#寻到叶子结点，可以得到结点中字符的编码
if root.c != ' ':
 codeTemp = codeStack.copy()
 code[ord(root.c) - 97] = codeTemp  
if treeStack == []: #根结点出栈，遍历结束
 break
codeStack.pop()  #编码栈出栈
#查看上一级结点是否访问完左右孩子
root = treeStack[-1]
temp = root.rchild
  if treeStack != []:
treeStack.append(temp)  #右孩子入栈
root.rchild = None#将结点右孩子设为空，代表已访问其右孩子
codeStack.append(1)  #1入编码栈
 return code

c解码：

#通过哈夫曼树解码
def decodeHuffman(T, strCode):
 decode = []
 index = 0
 while index < len(strCode):  #01编码字符串读完，解码结束
  root = T
  while root.lchild != None:  #找到叶子结点
if index < len(strCode):
 if strCode[index] == '0':
  root = root.lchild
 else:
  root = root.rchild
 index += 1
else:
 break
  decode.append(root.c)  #叶子结点存放的字符即为解码得到的字符
 return decode

d主函数：

if __name__ == '__main__':
 list = creatList()
 print("字符的权重如下")
 for i in range(len(list)):
  print("字符{}的权重为: {}".format(chr(i+97), list[i].weight))
 T = creatHuffman(list)
 code = encodeHuffman(T)
 print("\n字符编码结果如下")
 for i in range(len(code)):
  print(chr(i+97), end=' : ')
  for j in range(len(code[i])):
print(code[i][j], end='')
  print("")
 strCode = input("\n请输入编码：\n")
 #哈夫曼树在编码时被破坏，必须重建哈夫曼树
 list = creatList()
 T = creatHuffman(list)
 decode = decodeHuffman(T, strCode)
 print("解码结果如下：")
 for i in range(len(decode)):
  print(decode[i], end='')
 print("\n\n")
 datetime = datetime.datetime.now()
 print(datetime.strftime("%Y-%m-%d\n%H:%M:%S"))
 input("Press Enter to exit…")