Special topic of binary tree -- acwing 3384 Binary tree traversal (known preorder traversal, while building a tree, while outputting middle order traversal)

#define _CRT_SECURE_NO_WARNINGS 1
#include <bits/stdc++.h>

using namespace std;
//#define int long long
//#define map unordered_map

using namespace std;

void dfs()
{
    
    char ch; cin>>ch;
    
    if(ch == '#') return ;

    dfs();
    cout << ch << ' ';
    dfs();
}

int main()
{
    
    dfs();
    
    return 0;
}