How to use a vertical order traversal of a binary tree

#include <queue>
#include <vector>
#include <unordered_map> 
#include <climits>
using namespace std;
struct Node {
	int value;
	Node *left, *right;
	Node(int val)
	{
		this->value = val;
		this->left = this->right = NULL;
	}
};
void printTraversal(
	unordered_map<int, vector<int> > umap,
	int minKey, int maxKey)
{
	cout << "The vertical order traversal is: " << endl;
	for (int i = minKey; i <= maxKey; i++) 
		{
			for (int j=0;j<umap[i].size();j++)
			{
				cout << umap[i][j] << " " ;
			}
			cout << endl;
		}
}
void verticalOrderTraversal(Node* root)
{
	if (root == NULL)
		return;
    unordered_map<int, vector<int> > umap; 
	queue<pair<Node*, int>> q;
	
	q.push({root, 0}); // the horizontal distance of the root is 0.
	while (!q.empty())
	{
		// pop front node from the queue
		Node* node = q.front().first;
		int dist = q.front().second;
		q.pop();
		// insert in the correct hash value in the table.
        umap[dist].push_back(node->value); 
		// push its children, if any, into the queue.
		if (node->left)
			q.push({node->left, dist - 1});
		if (node->right)
			q.push({node->right, dist + 1});
	}
	
	cout << "The unordered hashmap is:" << endl;
	unordered_map< int,vector<int> > :: iterator it; 
	// if we get to know the min and max key,
	// then we can print the vertical traversal in
	// linear time as well.
	int maxKey = 0;
	int minKey = INT_MAX;
    for (it=umap.begin(); it!=umap.end(); it++) 
    { 
		cout << it->first << ": ";
        for (int i=0; i<it->second.size(); ++i) 
            cout << it->second[i] << " "; 
        cout << endl;
		// finding the min and max key
		if (it->first > maxKey)
			maxKey = it->first;
		if (it->first < minKey)
			minKey = it->first;
    }
	printTraversal(umap, minKey, maxKey);
}
// driver code
int main()
{
	Node* root = new Node(1);
	root->left = new Node(2);
	root->right = new Node(3);
	root->right->left = new Node(4);
	root->right->right = new Node(5);
	root->right->left->left = new Node(6);
	root->right->left->right = new Node(7);
	root->right->left->right->left = new Node(8);
	root->right->left->right->right = new Node(9);
	verticalOrderTraversal(root);
	return 0;
}