构造哈夫曼树

#include<iostream>
#include<stdio.h>
#include<string.h>
using namespace std;
#define N 50//叶子结点数
#define M 2*N-1//数中结点总数
typedef struct
{
    char data[5];//结点值
    int weight;//权重
    int parent;//双亲结点
    int lchild;//左孩子结点
    int rchild;//右孩子结点
}HTNode;
typedef struct
{
    char cd[N];//存放哈夫曼码
    int start;
}HCode;
void CreateHT(HTNode ht[],int n)//构造哈夫曼树
{
    int i,k,lnode,rnode;
    int min1,min2;
    for(i=0;i<2*n-1;i++)//所有结点的相关域置初值-1
        ht[i].parent=ht[i].lchild=ht[i].rchild=-1;
    for(i=n;i<2*n-1;i++)//构造哈夫曼树
    {
        min1=min2=32767;//lnode和rnode为最小权重的两个结点位置
        lnode=rnode=-1;
        for(k=0;k<=i-1;k++)
            if(ht[k].parent==-1)
            {
                if(ht[k].weight<min1)//只在尚未构造二叉树的结点中查找
                {
                    min2=min1;
                    rnode=lnode;
                    min1=ht[k].weight;
                    lnode=k;
                }
                else if(ht[k].weight<min2)
                {
                    min2=ht[k].weight;
                    rnode=k;
                }
            }
            ht[lnode].parent=i;
            ht[rnode].parent=i;
            ht[i].weight=ht[lnode].weight+ht[rnode].weight;
            ht[i].lchild=lnode;
            ht[i].rchild=rnode;
    }
}
void CreateHCode(HTNode ht[],HCode hcd[],int n)//构造哈夫曼编码
{
    int i,f,c;
    HCode hc;
    for(i=0;i<n;i++)//根据哈夫曼树求哈夫曼编码
    {
        hc.start=n;
        c=i;
        f=ht[i].parent;
        while(f!=-1)//循序知道树根结点
        {
            if(ht[f].lchild==c)//处理左孩子结点
                hc.cd[hc.start--]='0';
            else//处理右孩子结点
                hc.cd[hc.start--]='1';
            c=f;
            f=ht[f].parent;
        }
        hc.start++;//start指向哈夫曼编码最开始字符
        hcd[i]=hc;
    }
}

void DispHCode(HTNode ht[],HCode hcd[],int n)//输出哈夫曼编码
{
    int i,k;
    int sum=0,m=0,j;
    printf(" 输出哈夫曼编码:\n");//输出哈夫曼编码
    for(i=0;i<n;i++)
    {
        j=0;
        printf("%s:        ",ht[i].data);
        for(k=hcd[i].start;k<=n;k++)
        {
            printf(" %c",hcd[i].cd[k]);
            j++;
        }
        m+=ht[i].weight;
        sum+=ht[i].weight*j;
        printf("\n");
    }
    printf("\n 平均长度=%g\n",1.0*sum/m);
}
void main()
{
    int n=15,i;
    char*str[]={"The","of","a","to","and","in","that","he","is","at","on","for","His","are","be"};
    int fnum[]={1192,677,541,518,462,450,242,195,190,181,174,157,138,124,123};
    HTNode ht[M];
    HCode hcd[N];
    for(i=0;i<n;i++)
    {
        strcpy(ht[i].data,str[i]);
        ht[i].weight=fnum[i];
    }
    printf("\n");
    CreateHT(ht,n);
    CreateHCode(ht,hcd,n);
    DispHCode(ht,hcd,n);
    printf("\n");
}