struct HaffNode                      //哈夫曼树的结点结构
{int weight;            //权值int flag;                //标记int parent;            //双亲结点下标int leftChild;            //左孩子下标int rightChild;            //右孩子下标
};
struct Code           　　 //存放哈夫曼编码的数据元素结构
{int bit[MaxN];            //数组int start;            //编码的起始下标int weight;            //字符的权值char data;
};

#include <iostream>
using namespace std;
class Haffman
{HaffNode *hn;//= new HaffNode[2*n+1];Code *code;//=new Code[n];int n;
public:Haffman(int weight[], int n);                   //构造函数  时间复杂度O(n)Code* HaffmanCode(int n,Code* haffCode,char* c);//将haffman进行编码  时间复杂度O(n^2)void encoding(int n,Code* haffCode);            //输出权值与编码  时间复杂度O(n)void decoding(int n,Code* haffCode);            //输出译文  时间复杂度O(n)
};
Haffman::Haffman(int weight[], int n)
//建立叶结点个数为n权值为weight的哈夫曼树haffTree
{hn= new HaffNode[2*n+1];int j, m1, m2, x1, x2;
//哈夫曼树haffTree初始化。n个叶结点的哈夫曼树共有2n-1个结点for(int i = 0; i < 2 * n - 1 ; i++){if(i < n)hn[i].weight = weight[i];elsehn[i].weight = 0;hn[i].parent = 0;hn[i].flag   = 0;hn[i].leftChild = -1;hn[i].rightChild = -1;}for(int i = 0;i < n-1;i++){m1 = m2 = MaxValue;x1 = x2 = 0;for(j = 0; j < n+i;j++){if(hn[j].weight < m1 && hn[j].flag == 0){m2 = m1;  //m2放权值第2小的权值x2 = x1;  //m2放权值第2小的下标m1 = hn[j].weight;  //更新m1x1 = j;  //更新x1，下标
            }else if(hn[j].weight < m2 && hn[j].flag == 0){m2 = hn[j].weight;x2 = j;}}//将找出的两棵权值最小的子树合并为一棵子树hn[x1].parent  = n+i;hn[x2].parent  = n+i;hn[x1].flag    = 1;hn[x2].flag    = 1;hn[n+i].weight =hn[x1].weight+hn[x2].weight;hn[n+i].leftChild = x1;hn[n+i].rightChild = x2;}
}
//哈夫曼编码算法如下：
Code* Haffman::HaffmanCode(int n,Code* haffCode,char* c)
//由n个结点的哈夫曼树haffTree构造哈夫曼编码haffCode
{int child,parent;code=new Code[n];//求n个叶结点的哈夫曼编码for(int i = 0; i < n; i++){code->start = n-1;                       //不等长编码的最后一位为n-1code->weight = hn[i].weight;    //取得编码对应权值的字符child = i;parent = hn[child].parent;//由叶结点向上直到根结点while(parent != 0){if(hn[parent].leftChild == child)code->bit[code->start] = 0;  //左孩子结点编码0elsecode->bit[code->start] = 1;  //右孩子结点编码1code->start--;child = parent;parent = hn[child].parent;}//保存叶结点的编码和不等长编码的起始位for(int j = code->start+1; j < n; j++)haffCode[i].bit[j] = code->bit[j];haffCode[i].start  = code->start;haffCode[i].weight = code->weight;        //保存编码对应的权值haffCode[i].data=c[i];                  //存储原始数据
    }return haffCode;
}
void Haffman::encoding(int n,Code* haffCode)
{for(int i = 0; i < n; i++){cout << "Weight = " << haffCode[i].weight << "   Code = ";for(int j = haffCode[i].start+1; j < n; j++)cout << haffCode[i].bit[j];cout<<endl;}
}
void Haffman::decoding(int n,Code* haffCode)
{for(int i = 0; i < n; i++)cout<<haffCode[i].data;cout<<endl;
}

#include <iostream>
#include <stdlib.h>const int MaxValue = 10000;    //初始设定的权值最大值
const int MaxBit = 4;        //初始设定的最大编码位数
const int MaxN = 30;        //初始设定的最大结点个数
#include"Haffman.h"
using namespace std;int main()
{int n;//weight[]-权重（频率）数组int weight[] = {186,64,13,22,32,103,21,15,47,57,1,5,32,20,57,63,15,1,48,51,80,23,8,18,1,16,1};//a[]-按顺序存放各个字母char a[27]={' ','a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};char b[30];             //存放输入字符串int c[30];              //存放对应b数组的权值cout<<"请输入需要编码英文的字符串：";cin.getline(b,30);      //将输入的字符串存储在b数组中//将c数组权值与b数组字符串进行对应for(n=0;b[n]!='\0';n++){for(int l=0;l<27;l++){if(a[l]==b[n]){c[n]=weight[l];break;}}}if(n > MaxN){cout << "定义的n越界，修改MaxN! " << endl;exit(0);}//生成haffCode数组用作存储 编码后的数据Code* haffCode=new Code[n];Haffman hm(c, n);                   //调用生成Haffman树Code* co=hm.HaffmanCode(n,haffCode,b);//得到编码后数组cocout<<"编码后："<<endl;hm.encoding(n,co);                  //对co进行遍历输出cout<<"---------------------------------------"<<endl;cout<<"译码为:"<<endl;hm.decoding(n,co);                  //对编码数组操作得到译码return 0;
}