Check full binary tree

Java

public class Solution {
    /**
     * @param root: the given tree
     * @return: Whether it is a full tree
     */
		public boolean isFullTree(TreeNode root) {
			if (root == null) return true;
			Queue<TreeNode> queue = new LinkedList<>();
			queue.offer(root);
			while (!queue.isEmpty()) {
				TreeNode node = queue.poll();
				if (node.left == null && node.right == null) continue;
				if (node.left == null || node.right == null) return false; //都不是null
				queue.offer(node.left);
				queue.offer(node.right);
			}
			return true;
		}
}