Trees Title Difficulty Invert Binary Tree Easy Maximum Depth of Binary Tree Easy Diameter of Binary Tree Easy Balanced Binary Tree Easy Same Tree Easy Subset of Another Tree Easy Lowest Common Ancestor of a Binary Tree Medium Binary Tree Level Order Traversal Medium Binary Tree Right Side View Medium Count Good Nodes in Binary Tree Medium Validate Binary Search Tree Medium Kth Smallest Element in a BST Medium Construct Binary Tree from Preorder and Inorder Traversal Medium Binary Tree Maximum Path Sum Hard Serialize and Deserialize Binary Tree Hard