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/**
 * 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<Integer> rightSideView(TreeNode root) {
        List<Integer> l = new ArrayList<>();
        List<TreeNode> q2 = new ArrayList<>();
        List<TreeNode> q1 = new ArrayList<>();
        if(null == root) {
            return l;
        }
        q1.add(root);

        while(q1.size()>0) {
            TreeNode temp = null ;
            while(q1.size()>0) {
                temp = q1.remove(0);
                System.out.println("temp = " + temp.val);
                if(temp.left!= null) {
                    q2.add(temp.left);
                }
                if(temp.right!= null) {
                    q2.add(temp.right);
                }
                //q2.add(temp);
            }
            l.add(temp.val);
            q1.addAll(q2);
            q2.clear();
        }
        return l;

        
    }
}