Bottom View of Binary Tree

class Solution {
    
    class NodeInfo {
        int dis;
        Node node;
        NodeInfo(Node node, int dis) {
            this.dis = dis;
            this.node = node;
        }
    }
    
    //Function to return a list containing the bottom view of the given tree.
    public ArrayList <Integer> bottomView(Node root) {
        ArrayList<Integer> res = new ArrayList<> ();
        
        bottomViewUtil(root, res);
        return res;
    }
    
    private void bottomViewUtil(Node root, ArrayList<Integer> res) {
        Queue<NodeInfo> que = new LinkedList<> ();
        int[] width = new int[] {Integer.MAX_VALUE, Integer.MIN_VALUE};
        Map<Integer, Integer> map = new HashMap<> ();
        
        que.add(new NodeInfo(root, 0));
        
        while(que.isEmpty() == false) {
            NodeInfo temp = que.remove();
            
            map.put(temp.dis, temp.node.data);
            
            width[0] = Math.min(width[0], temp.dis);
            width[1] = Math.max(width[1], temp.dis);
            
            if(temp.node.left != null) 
                que.add(new NodeInfo(temp.node.left, temp.dis - 1));
            if(temp.node.right != null) 
                que.add(new NodeInfo(temp.node.right, temp.dis + 1));
        }
        
        
        for(int i = width[0]; i <= width[1]; i++) {
            res.add(map.get(i));
        }
        
    }
    
}