1702 - Tree Traversals.cpp

/*
Problem Name: Tree Traversals
Problem Link: https://cses.fi/problemset/task/1702
Author: Sachin Srivastava (mrsac7)
*/
#include<bits/stdc++.h>
using namespace std;
 
#define int long long
#define endl '\n'
 
vector<int> pre, in;
int a[100005];
int x = 0, n;
void post(int l = 0, int h = n-1) {
    if (l > h) {
        x--;
        return;
    }
    int i = a[pre[x]];
    ++x;
    post(l, i-1);
    ++x;
    post(i+1, h);
    cout<<in[i]<<' ';
}
signed main(){
    ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    #ifdef LOCAL
    freopen("input.txt", "r" , stdin);
    freopen("output.txt", "w", stdout);
    #endif
    
    cin>>n;
    for (int i = 0; i < n; i++) {
        int x; cin>>x;
        pre.push_back(x);
    }
    for (int i = 0; i < n; i++) {
        int x; cin>>x;
        in.push_back(x);
        a[x] = i;
    }
    post();
}