利用Python和C語(yǔ)言分別實(shí)現(xiàn)哈夫曼編碼
1.C語(yǔ)言實(shí)現(xiàn)
1.1代碼說(shuō)明
a 創(chuàng)建雙向鏈表:
在創(chuàng)建哈夫曼樹(shù)的過(guò)程中,需要不斷對(duì)結(jié)點(diǎn)進(jìn)行更改和刪除,所以選用雙向鏈表的結(jié)構(gòu)更容易
'''C #include <stdlib.h> #include <stdio.h> #include <windows.h> //哈夫曼樹(shù)結(jié)構(gòu)體,數(shù)據(jù)域存儲(chǔ)字符及其權(quán)重 typedef struct node { char c; int weight; struct node *lchild, *rchild; }Huffman, *Tree; //雙向鏈表結(jié)構(gòu)體,數(shù)據(jù)域存儲(chǔ)哈夫曼樹(shù)結(jié)點(diǎn) typedef struct list { Tree root; struct list *pre; struct list *next; }List, *pList; //創(chuàng)建雙向鏈表,返回頭結(jié)點(diǎn)指針 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創(chuàng)建棧結(jié)構(gòu):
解碼過(guò)程需要用到兩個(gè)棧,一個(gè)用來(lái)存放樹(shù)結(jié)點(diǎn),一個(gè)用來(lái)存放碼0和1
'''C #define STACK_INIT_SIZE 100//棧初始開(kāi)辟空間大小 #define STACK_INCREMENT 10 //棧追加空間大小 //字符棧結(jié)構(gòu)體,存放編碼'0'和'1' typedef struct { char *base; char *top; int size; }charStack; //棧初始化 charStack charStackInit() { charStack s; s.base = (char *)malloc(sizeof(char)*STACK_INIT_SIZE); s.top = s.base; s.size = STACK_INIT_SIZE; return s; } //入棧 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++; } //出棧 char charPop(charStack *s) { if(s->top != s->base) { s->top--; return *s->top; } return -1; } //得到棧頂元素,但不出棧 char charGetTop(charStack *s) { s->top--; char temp = *s->top; s->top++; return temp; } //棧結(jié)構(gòu)體,存放哈夫曼樹(shù)結(jié)點(diǎn) typedef struct { Huffman *base; Huffman *top; int size; }BiStack; //棧初始化 BiStack stackInit() { BiStack s; s.base = (Huffman *)malloc(sizeof(Huffman)*STACK_INIT_SIZE); s.top = s.base; s.size =STACK_INIT_SIZE; return s; } //入棧 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++; } //出棧 Huffman pop(BiStack *s) { Huffman temp; s->top--; temp = *s->top; return temp; } //得到棧頂元素,但不出棧 Huffman getTop(BiStack s) { Huffman temp; s.top--; temp = *s.top; return temp; } char stack[7][10]; //記錄a~g的編碼 //遍歷棧,得到字符c的編碼 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 創(chuàng)建哈夫曼樹(shù):
'''C //通過(guò)雙向鏈表創(chuàng)建哈夫曼樹(shù),返回根結(jié)點(diǎn)指針 Tree creatHuffman(pList head) { pList list1 = NULL; pList list2 = NULL; pList index = NULL; Tree root = NULL; while(head->next != NULL)//鏈表只剩一個(gè)結(jié)點(diǎn)時(shí)循環(huán)結(jié)束,此結(jié)點(diǎn)數(shù)據(jù)域即為哈夫曼樹(shù)的根結(jié)點(diǎn) { list1 = head; list2 = head->next; index = list2->next; root = (Tree)malloc(sizeof(Huffman)); while(index != NULL) //找到鏈表中權(quán)重最小的兩個(gè)結(jié)點(diǎn)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設(shè)為新結(jié)點(diǎn)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; } //新結(jié)點(diǎn)字符統(tǒng)一設(shè)為空格,權(quán)重設(shè)為list1與list2權(quán)重之和 root->c = ' '; root->weight = list1->root->weight + list2->root->weight; //list1數(shù)據(jù)域替換成新結(jié)點(diǎn),并刪除list2 list1->root = root; list2->pre->next = list2->next; if(list2->next != NULL) list2->next->pre = list2->pre; } return head->root; }
d編碼:
'''C char stack[7][10]; //記錄a~g的編碼 //遍歷棧,得到字符c的編碼 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++; } } //通過(guò)哈夫曼樹(shù)編碼 void encodeHuffman(Tree T) { BiStack bs = stackInit(); charStack cs = charStackInit(); Huffman root = *T; Tree temp = NULL; push(&bs, root);//根結(jié)點(diǎn)入棧 while(bs.top != bs.base)//棧空表示遍歷結(jié)束 { root = getTop(bs); temp = root.lchild; //先訪問(wèn)左孩子 while(temp != NULL) //左孩子不為空 { //將結(jié)點(diǎn)左孩子設(shè)為空,代表已訪問(wèn)其左孩子 root.lchild = NULL; pop(&bs); push(&bs, root); //左孩子入棧 root = *temp; temp = root.lchild; push(&bs, root); //'0'入字符棧 charPush(&cs, '0'); } temp = root.rchild; //后訪問(wèn)右孩子 while(temp == NULL) //右孩子為空,代表左右孩子均已訪問(wèn),結(jié)點(diǎn)可以出棧 { //結(jié)點(diǎn)出棧 root = pop(&bs); //尋到葉子結(jié)點(diǎn),可以得到結(jié)點(diǎn)中字符的編碼 if(root.c != ' ') traverseStack(cs, root.c); charPop(&cs); //字符棧出棧 if(bs.top == bs.base) break; //根結(jié)點(diǎn)出棧,遍歷結(jié)束 //查看上一級(jí)結(jié)點(diǎn)是否訪問(wèn)完左右孩子 root = getTop(bs); temp = root.rchild; } if(bs.top != bs.base) { //將結(jié)點(diǎn)右孩子設(shè)為空,代表已訪問(wèn)其右孩子 root.rchild = NULL; pop(&bs); push(&bs, root); //右孩子入棧 root = *temp; push(&bs, root); //'1'入字符棧 charPush(&cs, '1'); } } }
e解碼:
'''C char decode[100];//記錄解碼得到的字符串 //通過(guò)哈夫曼樹(shù)解碼 void decodeHuffman(Tree T, char *code) { int cnt = 0; Tree root; while(*code != '\0')//01編碼字符串讀完,解碼結(jié)束 { root = T; while(root->lchild != NULL) //找到葉子結(jié)點(diǎn) { if(*code != '\0') { if(*code == '0') root = root->lchild; else root = root->rchild; code++; } else break; } decode[cnt] = root->c; //葉子結(jié)點(diǎn)存放的字符即為解碼得到的字符 cnt++; } }
f主函數(shù):
'''C void main() { pList pl = creatList(); printf("字符的權(quán)重如下\n"); for(pList l = pl; l->next != NULL; l = l->next) printf("字符%c的權(quán)重是 %d\n", l->root->c, l->root->weight); Tree T = creatHuffman(pl); encodeHuffman(T); printf("\n\n字符編碼結(jié)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請(qǐng)輸入編碼:\n"); scanf("%s", code); printf("解碼結(jié)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運(yùn)行結(jié)果
2.Python實(shí)現(xiàn)
2.1代碼說(shuō)明
a創(chuàng)建哈夫曼樹(shù):
#coding=gbk import datetime import time from pip._vendor.distlib.compat import raw_input #哈夫曼樹(shù)結(jié)點(diǎn)類(lèi) class Huffman: def __init__(self, c, weight): self.c = c self.weight = weight self.lchild = None self.rchild = None #創(chuàng)建結(jié)點(diǎn)左右孩子 def creat(self, lchild, rchild): self.lchild = lchild self.rchild = rchild #創(chuàng)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 #通過(guò)列表創(chuàng)建哈夫曼樹(shù),返回樹(shù)的根結(jié)點(diǎn) def creatHuffman(list): while len(list) > 1:#列表只剩一個(gè)結(jié)點(diǎn)時(shí)循環(huán)結(jié)束,此結(jié)點(diǎn)即為哈夫曼樹(shù)的根結(jié)點(diǎn) i = 0 j = 1 k = 2 while k < len(list): #找到列表中權(quán)重最小的兩個(gè)結(jié)點(diǎn)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) #新結(jié)點(diǎn)字符統(tǒng)一設(shè)為空格,權(quán)重設(shè)為list1與list2權(quán)重之和 if list[i].weight < list[j].weight:#list1和list2設(shè)為新結(jié)點(diǎn)的左右孩子 root.creat(list[i], list[j]) else: root.creat(list[j], list[i]) #list1數(shù)據(jù)域替換成新結(jié)點(diǎn),并刪除list2 list[i] = root list.remove(list[j]) return list[0]
b編碼:
#通過(guò)哈夫曼樹(shù)編碼 def encodeHuffman(T): code = [[], [], [], [], [], [], []] #列表實(shí)現(xiàn)棧結(jié)構(gòu) treeStack = [] codeStack = [] treeStack.append(T) while treeStack != []: #??沾肀闅v結(jié)束 root = treeStack[-1] temp = root.lchild while temp != None: #將結(jié)點(diǎn)左孩子設(shè)為空,代表已訪問(wèn)其左孩子 root.lchild = None #左孩子入棧 treeStack.append(temp) root = temp temp = root.lchild #0入編碼棧 codeStack.append(0) temp = root.rchild#后訪問(wèn)右孩子 while temp == None: #右孩子為空,代表左右孩子均已訪問(wèn),結(jié)點(diǎn)可以出棧 root = treeStack.pop() #結(jié)點(diǎn)出棧 #尋到葉子結(jié)點(diǎn),可以得到結(jié)點(diǎn)中字符的編碼 if root.c != ' ': codeTemp = codeStack.copy() code[ord(root.c) - 97] = codeTemp if treeStack == []: #根結(jié)點(diǎn)出棧,遍歷結(jié)束 break codeStack.pop() #編碼棧出棧 #查看上一級(jí)結(jié)點(diǎn)是否訪問(wèn)完左右孩子 root = treeStack[-1] temp = root.rchild if treeStack != []: treeStack.append(temp) #右孩子入棧 root.rchild = None#將結(jié)點(diǎn)右孩子設(shè)為空,代表已訪問(wèn)其右孩子 codeStack.append(1) #1入編碼棧 return code
c解碼:
#通過(guò)哈夫曼樹(shù)解碼 def decodeHuffman(T, strCode): decode = [] index = 0 while index < len(strCode): #01編碼字符串讀完,解碼結(jié)束 root = T while root.lchild != None: #找到葉子結(jié)點(diǎn) if index < len(strCode): if strCode[index] == '0': root = root.lchild else: root = root.rchild index += 1 else: break decode.append(root.c) #葉子結(jié)點(diǎn)存放的字符即為解碼得到的字符 return decode
d主函數(shù):
if __name__ == '__main__': list = creatList() print("字符的權(quán)重如下") for i in range(len(list)): print("字符{}的權(quán)重為: {}".format(chr(i+97), list[i].weight)) T = creatHuffman(list) code = encodeHuffman(T) print("\n字符編碼結(jié)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請(qǐng)輸入編碼:\n") #哈夫曼樹(shù)在編碼時(shí)被破壞,必須重建哈夫曼樹(shù) list = creatList() T = creatHuffman(list) decode = decodeHuffman(T, strCode) print("解碼結(jié)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…")
2.2運(yùn)行結(jié)果
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