根据中序和后序遍历确定前序

先序和后序可以确定根
再利用根在中序中确定左右子树

#include<bits/stdc++.h>
using namespace std;
int const N=37;
int const M=25e4+7;
int n;
int h[N],z[N];
vector<int>v;
void dfs(int l1,int r1,int l2,int r2){
    if(l1>r1||l2>r2) return ;
    for(int i=l1;i<=r1;++i){
        if(z[i]==h[r2]){
            v.push_back(h[r2]);
            dfs(l1,i-1,l2,l2-1+i-l1);
            dfs(i+1,r1,l2+i-l1,r2-1);
            break;
        }
    }
}
int main(){
    cin >> n;
    for(int i=1;i<=n;++i) cin >> h[i];
    for(int i=1;i<=n;++i) cin >> z[i];
    dfs(1,n,1,n);
    cout << "Preorder: ";
    int len=v.size();
    for(int i=0;i<len;++i){
        cout << v[i];
        if(i!=len-1) cout << " ";
    }
    return 0;
}