LeetCode Medium: Binary Tree Zigzag Level Order Traversal

My solution using BFS like- Level Order Traversal using Queue snapshots:

 

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    public List<List> zigzagLevelOrder(TreeNode root) {
        //BFS
        List<List> result = new LinkedList<>();
        if (root == null)
            return result;
        
        Queue q = new LinkedList<>();
        q.add(root);
        while (!q.isEmpty()) {
            int nextLevelSize = q.size();
            LinkedList level = new LinkedList<>();
            
            for (int i=0; i<nextLevelSize; i++) {
                TreeNode current = q.remove();
                
                if (result.size()%2 == 0) // level is an odd level to be added
                    level.add(current.val);
                else //even-level has elements added in reverse
                    level.addFirst(current.val);
                
                if (current.left != null)
                    q.add(current.left);
                if (current.right != null)
                    q.add(current.right);
            }
            
            result.add(level);
        }
        
        return result;
    }
}

 

Feel free to point out suggestions for improvement and share your outlook!

 

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