赫夫曼编码

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用赫夫曼树进行编码是我们处理数据压缩常用的方法。请同学们用赫夫曼编码方法保存你班同学《数据结构》课程的期终考试成绩。

#include <stdio.h>#include <stdlib.h>#include <string.h>#include <malloc.h>#define OK         1#define maxnn 100000typedef struct student{   //学生类，储存学生的姓名成绩char name[10];double score;}student,*pstudent;typedef struct HTNode{     //赫夫曼树的节点student stu;int parent,lchild,rchild;}HTNode,*HuffmanTree;typedef char** HuffmanCode;void Select(HuffmanTree HT,int i,int &s1,int &s2){  //选出最大的两个节点int j,s3;double min,min2,max;max=min = HT[1].stu.score;s1 = 1;s3 = 1;for (j = 1; j <= i; j++){if (min > HT[j].stu.score){min = HT[j].stu.score;s1 = j;}if (max < HT[j].stu.score){max = HT[j].stu.score;s3 = j;}}HT[s1].stu.score = HT[s3].stu.score+1;s2 = 1;min2 = HT[1].stu.score;for (j = 1; j <= i; j++){if (min2 >HT[j].stu.score){min2 = HT[j].stu.score;s2 = j;}}HT[s1].stu.score = min;}void HuffmanCoding(HuffmanTree &HT,HuffmanCode &HC,pstudent w,int n){  //建立赫夫曼树int m;int i;int s1,s2;char *cd;int start;HuffmanTree p;if(n<=1)return;m=2*n-1;HT=(HuffmanTree)malloc((m+1)*sizeof(HTNode));for(p=HT+1,i=1;i<=n;i++,p++){p->stu.score=w[i].score;strcpy(p->stu.name,w[i].name);}for(;i<=m;i++,p++){p->lchild=p->parent=p->rchild=p->stu.score=0;}for(i=n+1;i<=m;i++){Select(HT,i-1,s1,s2);HT[s1].parent=HT[s2].parent=i;HT[i].lchild=s1;HT[i].rchild=s2;HT[i].stu.score=HT[s1].stu.score+HT[s2].stu.score;HT[s1].stu.score=HT[s2].stu.score=maxnn;}HC=(HuffmanCode)malloc((n+1)*sizeof(char *));               //进行赫夫曼编码for(i=1;i<=n;i++){  cd=(char *)malloc(n*sizeof(char));cd[n-1]='\0';start=n-1;int c=i;int f=HT[i].parent;for(;f!=0;c=f,f=HT[f].parent){if(HT[f].lchild==c)cd[--start]='0';elsecd[--start]='1';}if(start!=0){int j;for(j=0;j<n-start;j++,start++)cd[j]=cd[start];cd[j]='\0';}HC[i]=(char*)malloc((n-start)*sizeof(char));strcpy(HC[i],cd);}free(cd);for(p=HT+1,i=1;i<=n;i++,p++){p->stu.score=w[i].score;strcpy(p->stu.name,w[i].name);}}int main(){HuffmanTree HT;HuffmanCode HC;int n;printf("学生人数：");scanf("%d",&n);pstudent ps;ps=(pstudent)malloc((n+1)*sizeof(student));printf("姓名   成绩   \n");for(int i=1;i<=n;i++)scanf("%s %lf",ps[i].name,&ps[i].score);HuffmanCoding(HT,HC,ps,n);for(int i=1;i<=n;i++){printf("姓名   成绩   赫夫曼编码\n");printf(" %s    %.1lf     %s\n",HT[i].stu.name,HT[i].stu.score,HC[i]);}return OK;}

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