leetcode——114.二叉树展开为链表

public void flatten(TreeNode root) {
        if(root == null){
            return;
        }else{
            if(root.left == null){
                flatten(root.right);
            }else{
                TreeNode node = root;
                TreeNode nodeRight = root.right;
                node.right = root.left;
                root.left = null;
                while(node.right != null){
                    node = node.right;
                }
                node.right = nodeRight;
                flatten(root.right);
            }
        }
}