一、先建立树再后序

#include <iostream>

using namespace std;

/*
    先建树再后序。
*/

string pre,in;
int n;

struct node{
    char value;
    node *left;
    node *right;
};

int findmid(int l, int r){
    for(int i = 0;i < pre.size();i++){
        for(int j = l;j <= r;j++){
            if(pre[i] == in[j]){
                return j;
            }
        }
    }
}

node* creat(int l,int r){
    node *T;
    if(l > r){
        T = NULL;
    }else{
        T = (struct node*)malloc(sizeof(node));
        int mid = findmid(l, r);
        T->value = in[mid];
        T->left = creat(l, mid-1);
        T->right = creat(mid+1, r);
    }
    return T;
}

void PostOrderTra(node *T){
    if(T != NULL){
        PostOrderTra(T->left);
        PostOrderTra(T->right);
        cout << T->value;
    }
}

int main()
{
    cin >> pre >> in;
    node *T = (struct node *)malloc(sizeof(node));
    T = creat(0, ...