递归二叉树知先中序求后序遍历

#include<iostream>
#include<cstring>
#include<cstdio>
#include<cstdlib>
#include<map>
using namespace std;
char str1[30],str2[30];
struct node
{
    char ch;
    node *l,*r;
};
node* build(char ch,node *l,node *r)
{
    node *p=(struct node *)malloc(sizeof(node));
    p->ch=ch,p->l=l,p->r=r;
    return p;
}
node *rebuild(int pos,int l,int r)
{
    if(l>r){return NULL;}
    if(l==r){node *v=build(str1[pos],NULL,NULL);return v;}
    int p;
    for(int i=l;i<=r;i++)
    {
        if(str2[i]==str1[pos]){p=i;break;}
    }
    node *ll=rebuild(pos+1,l,p-1);
    node *rr=rebuild(pos+p-l+1,p+1,r);
    node *u=build(str1[pos],ll,rr);
    return u;
}
void post(node *p)
{
    if(p==NULL) return;
    post(p->l);
    post(p->r);
    printf("%c",p->ch);
}
int main()
{
    while(scanf("%s%s",str1+1,str2+1)!=EOF)
    {
        post(rebuild(1,1,strlen(str2+1)));
        printf("\n");
    }
    return 0;
}重点在设计递归,其次用下链表数据结构
#include<iostream>
#include<cstring>
#include<c