poj 2255（二叉树遍历）

#include<iostream>
#include<cstring>
using namespace std;
char a[27],b[27];
int L;
struct Node{
    int data;
    Node*left;
    Node*right;
};
int find(int astart){
    for(int i=0;i<L;i++){
        if(a[astart] == b[i])
            return i;
    }
}
Node*rebuild(int len,int astart,int bstart){
    if(len<=0)return NULL;
    Node*newnode = new Node;
    newnode->data = a[astart];
    if(len==1){
        newnode->left = newnode->right = NULL;
        return newnode; 
    }
    int p = find(astart);
    if(bstart==p){
        newnode->left = NULL;
        newnode->right = rebuild(len-1,astart+1,bstart+1);
    }
    else if(bstart+len-1==p){
        newnode->right = NULL;
        newnode->left = rebuild(len-1,astart+1,bstart);
    }
    else{
        newnode->left = rebuild(p-bstart,astart+1,bstart);
        newnode->right = rebuild(len-1-(p-bstart),astart+p-bstart+1,p+1);
    }
    return newnode;
}
void print(Node*p){
    if(p!=NULL){
        print(p->left);
        print(p->right);
        printf("%c",p->data);
    }
}
int main(){
    int len;
    while(cin>>a>>b){
        len = strlen(a);
        L = len;
        print(rebuild(len,0,0));
        cout<<endl;
    }
    return 0;
}