C++数据结构与算法之哈夫曼树的实现方法

#include <iostream>using namespace std;#if !defined(_HUFFMANTREE_H_)#define _HUFFMANTREE_H_/* * 哈夫曼树结构 */class HuffmanTree{public:  unsigned int Weight;  unsigned int Parent;  unsigned int lChild;  unsigned int rChild;};typedef char **HuffmanCode;/* * 从结点集合中选出权值最小的两个结点 * 将值分别赋给s1和s2 */void Select(HuffmanTree* HT,int Count,int *s1,int *s2){  unsigned int temp1=0;  unsigned int temp2=0;  unsigned int temp3;  for(int i=1;i<=Count;i++)  {    if(HT[i].Parent==0)    {      if(temp1==0)      {        temp1=HT[i].Weight;        (*s1)=i;      }      else      {        if(temp2==0)        {          temp2=HT[i].Weight;          (*s2)=i;          if(temp2<temp1)          {            temp3=temp2;            temp2=temp1;            temp1=temp3;            temp3=(*s2);            (*s2)=(*s1);            (*s1)=temp3;          }        }        else        {          if(HT[i].Weight<temp1)          {            temp2=temp1;            temp1=HT[i].Weight;            (*s2)=(*s1);            (*s1)=i;          }          if(HT[i].Weight>temp1&&HT[i].Weight<temp2)          {            temp2=HT[i].Weight;            (*s2)=i;          }        }      }    }  }}/* * 霍夫曼编码函数 */void HuffmanCoding(HuffmanTree * HT,          HuffmanCode * HC,          int *Weight,          int Count){  int i;  int s1,s2;  int TotalLength;  char* cd;  unsigned int c;  unsigned int f;  int start;  if(Count<=1) return;  TotalLength=Count*2-1;  HT = new HuffmanTree[(TotalLength+1)*sizeof(HuffmanTree)];  for(i=1;i<=Count;i++)  {    HT[i].Parent=0;    HT[i].rChild=0;    HT[i].lChild=0;    HT[i].Weight=(*Weight);    Weight++;  }  for(i=Count+1;i<=TotalLength;i++)  {    HT[i].Weight=0;    HT[i].Parent=0;    HT[i].lChild=0;    HT[i].rChild=0;  }  //建造哈夫曼树  for(i=Count+1;i<=TotalLength;++i)  {    Select(HT, i-1, &s1, &s2);    HT[s1].Parent = i;    HT[s2].Parent = i;    HT[i].lChild = s1;    HT[i].rChild = s2;    HT[i].Weight = HT[s1].Weight + HT[s2].Weight;  }  //输出霍夫曼编码  (*HC)=(HuffmanCode)malloc((Count+1)*sizeof(char*));  cd = new char[Count*sizeof(char)];  cd[Count-1]='/0';  for(i=1;i<=Count;++i)  {    start=Count-1;    for(c = i,f = HT[i].Parent; f != 0; c = f, f = HT[f].Parent)    {      if(HT[f].lChild == c)        cd[--start]='0';      else        cd[--start]='1';      (*HC)[i] = new char [(Count-start)*sizeof(char)];      strcpy((*HC)[i], &cd[start]);    }  }  delete [] HT;  delete [] cd;}/* * 在字符串中查找某个字符 * 如果找到，则返回其位置 */int LookFor(char *str, char letter, int count){  int i;  for(i=0;i<count;i++)  {    if(str[i]==letter) return i;  }  return -1;}void OutputWeight(char *Data,int Length,         char **WhatLetter,         int **Weight,int *Count){  int i;  char* Letter = new char[Length];  int* LetterCount = new int[Length];  int AllCount=0;  int Index;  int Sum=0;  float Persent=0;  for(i=0;i<Length;i++)  {    if(i==0)    {      Letter[0]=Data[i];      LetterCount[0]=1;      AllCount++;    }    else    {      Index=LookFor(Letter,Data[i],AllCount);      if(Index==-1)      {        Letter[AllCount]=Data[i];        LetterCount[AllCount]=1;        AllCount++;      }      else      {        LetterCount[Index]++;      }    }  }  for(i=0;i<AllCount;i++)  {    Sum=Sum+LetterCount[i];  }  (*Weight) = new int[AllCount];  (*WhatLetter) = new char[AllCount];  for(i=0;i<AllCount;i++)  {    Persent=(float)LetterCount[i]/(float)Sum;    (*Weight)[i]=(int)(1000*Persent);    (*WhatLetter)[i]=Letter[i];  }  (*Count)=AllCount;  delete [] Letter;  delete [] LetterCount;}#endifvoid main(){  HuffmanTree * HT = NULL;  HuffmanCode HC;  char Data[100];  char *WhatLetter;  int *Weight;  int Count;  cout<<"请输入一行文本数据:"<<endl;  cin>>Data;  cout<<endl;  OutputWeight(Data,strlen(Data),    &WhatLetter,    &Weight,    &Count);  HuffmanCoding(HT, &HC, Weight, Count);  cout<<"字符 出现频率 编码结果"<<endl;  for(int i = 0; i<Count; i++)  {    cout<<WhatLetter[i]<<"   ";    cout<<Weight[i]/1000.0<<"%/t";    cout<<HC[i+1]<<endl;  }  cout<<endl;}