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

// Structure representing each node of the binary tree
struct Node {
    // Value stored in the node
    int data;
    // Pointer to the left child
    Node* left;
    // Pointer to the right child
    Node* right;
    // Constructor to initialize a node with a value
    Node(int val) : data(val), left(nullptr), right(nullptr) {}
};

// Class containing the logic for top view
class Solution {
public:
    // Function to return the top view of the binary tree
    vector<int> topView(Node* root) {
        // Create a vector to store the final answer
        vector<int> ans;

        // If the tree is empty, return an empty result
        if (root == NULL) {
            return ans;
        }

        // Create a map to store vertical level -> node value (only first encountered)
        map<int, int> mpp;

        // Create a queue for BFS that stores {node, vertical_level}
        queue<pair<Node*, int>> q;

        // Push the root node with vertical level 0
        q.push({root, 0});

        // Start BFS traversal
        while (!q.empty()) {
            // Extract the front element of the q