Hifipsysta-1734-二叉树遍历

#include<iostream>
#include<cstring>
using namespace std;
const int MAXN = 27;
struct node{
    char data;
    node* lchild;
    node* rchild;
    //node(char c): data(c),lchild(NULL),rchild(NULL){};
};
int pre[MAXN], in[MAXN];
node* create(int preL, int preR, int inL, int inR){
    if(preL > preR){
        return NULL;
    }
    node* root = new node;
    root->data = pre[preL];
    int k;
    for(k = inL; k < inR; k++){
        if(in[k] == pre[preL]){
            break;
        }
    }
    int numLeft = k-inL;
    root -> lchild = create(preL+1, preL + numLeft, inL, k-1);
    root -> rchild = create(preL+numLeft+1, preR, k+1, inR);
    return root;
}
void postorder(node* root){
    if(root == NULL){
        return;
    }
    postorder(root->lchild);
    postorder(root->rchild);
    printf("%c", root->data);
}
int main(){
    string str;
    while(getline(cin, str)){
        for(int i=0;i<str.size();i++){
            pre[i]=str[i];
        }
        getline(cin, str);
        for(int i=0;i<str.size();i++){
            in[i]=str[i];
        }
        node* root = create(0, str.size()-1, 0, str.size()-1);
        postorder(root);
        cout<<endl;
        memset(pre, 0, sizeof(pre));
        memset(in, 0, sizeof(in));
    }
    return 0;
}