515. find the maximum value in each tree row

Follow the last article , One more time leetcode My daily question , Topic link ：515. Find the maximum in each tree row
The title is as follows ：

Given the root node of a binary tree root , Please find... In the binary tree Each layer Of Maximum .

This problem uses the sequence traversal routine of binary tree , The code is as follows ：

    public static List<Integer> largestValues(TreeNode root) {
    
        List<Integer> maxList = new ArrayList<>();
        if(root == null){
    
            return maxList;
        }

        LinkedList<TreeNode> list = new LinkedList<>();
        list.addFirst(root);

        while(!list.isEmpty()){
    

            int size = list.size();
            // Here is a brief note 
            int max = Integer.MIN_VALUE;

            for (int i = 0; i < size; i++) {
    
                TreeNode treeNode = list.removeFirst();
                if(treeNode.left != null){
    
                    list.addLast(treeNode.left );
                }
                if(treeNode.right != null){
    
                    list.addLast(treeNode.right);
                }
                int val = treeNode.val;
                max = max > val ? max : val;
            }

            maxList.add(max);
        }
        return maxList;
    }