问题描述

为什么运行后打印的树上没有节点，而且下面也没有编码

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;  

#define N 10         // 带编码字符的个数，即树中叶结点的最大个数
#define M (2*N-1)    // 树中总的结点数目  

class HTNode{        // 树中结点的结构
public:
     char data;
     int weight;
     int parent,lchild,rchild;
};                      

class HTCode{
public:
    char data;      // 待编码的字符
    int weight;     // 字符的权值
    char code[N];   // 字符的编码
};  

void Init(HTCode hc[], int *n){
// 初始化，读入待编码字符的个数n，从键盘输入n个字符和n个权值
    int i;
    cout<<"输入字符个数：";
    cin>>*n;  

    cout<<"输入"<<*n<<"个字符"; 

    fflush(stdin);
    for(i=1; i<=*n; ++i)
        cin>>hc[i].data;

    cout<<"输入"<<*n<<"个权值";  

    for(i=1; i<=*n; ++i)
        cin>>hc[i].weight;
    fflush(stdin);
}//  

void Select(HTNode ht[], int k, int *s1, int *s2){
// ht[1...k]中选择parent为0，并且weight最小的两个结点，其序号由指针变量s1，s2指示
    int i;
    for(i=1; i<=k && ht[i].parent != 0; i++){
        ; ;
    }
    *s1 = i;  

    for(i=1; i<=k; ++i){
        if(ht[i].parent==0 && ht[i].weight<ht[*s1].weight)
            *s1 = i;
    }  

    for(i=1; i<=k; i++){
        if(ht[i].parent==0 && i!=*s1)
            break;
    }
    *s2 = i;  

    for(i=1; i<=k; i++){
        if(ht[i].parent==0 && i!=*s1 && ht[i].weight<ht[*s2].weight)
            *s2 = i;
    }
}
void dayin(HTNode ht[],int k ,int n)
{
    if(k==0)
    {
        return;
    }
    for (int i=0;i<n;i++)
    {
        cout<<" ";
    }
    if(ht[k].parent!=0)
    {
        cout<<"|_";
    }
    else {
        cout<<" ";
    }
    cout<<ht[k].data<<endl;
    int L=ht[k].lchild;
    int R=ht[k].rchild;
    dayin(ht,R,n+2);
    dayin(ht,L,n+2);
}

void HuffmanCoding(HTNode ht[],HTCode hc[],int n){
// 构造Huffman树ht，并求出n个字符的编码
    char cd[N];
    int i,j,m,c,f,s1,s2,start;
    m = 2*n-1;  

    for(i=1; i<=m; i++){
        if(i <= n)
            ht[i].weight = hc[i].weight;
        else
            ht[i].parent = 0;
        ht[i].parent = ht[i].lchild = ht[i].rchild = 0;
    }  

    for(i=n+1; i<=m; 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;
    }  

    cd[n-1] = '';  

    for(i=1; i<=n; i++){
        start = n-1;
        for(c=i,f=ht[i].parent; f; c=f,f=ht[f].parent){
            if(ht[f].lchild == c)
                cd[--start] = '0';
            else
                cd[--start] = '1';
        }
        strcpy(hc[i].code, &cd[start]);
    }
    dayin(ht, 2*n-1, 0);
}  

int main()
{
    int i,m,n,w[N+1];
    HTNode ht[M+1];
    HTCode hc[N+1];
    Init(hc, &n);     // 初始化
    HuffmanCoding(ht,hc,n);   // 构造Huffman树，并形成字符的编码  

    for(i=1; i<=n; ++i)
    cout<<hc[i].data<<"---"<<hc[i].weight<<endl;
    //dayin(ht, 2*n-1, 0);   

    return 0;
}