Preorder Traversal

Pre order : Root Left Right
In order : Left Root Right
Post order : Left Right Root

Pre -> before
In -> Middle
Post -> After

Code
We will implement it using recursion

#include <bits/stdc++.h>
using namespace std;

class Node
{
public:
    int val;
    Node *right;
    Node *left;
    Node(int value)
    {
        this->val = value;
        this->right = NULL;
        this->left = NULL;
    }
};

void preorder(Node *root)
{
    if (root == NULL)
        return;
    cout << root->val << " "; // root
    preorder(root->left);     // left
    preorder(root->right);    // right
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    Node *root = new Node(10);
    Node *a = new Node(12);
    Node *b = new Node(20);
    Node *c = new Node(30);
    Node *d = new Node(40);
    Node *e = new Node(50);
    Node *f = new Node(60);

    root->left = a;
    root->right = b;
    a->left = c;
    b->left = d;
    b->right = e;

    preorder(root);
    return 0;
}