BST 中的最小節點差值 | Easy| LeetCode#530. Minimum Absolute Difference in BST
將二元樹展平為Linked List| Medium | LeetCode#114. Flatten Binary Tree to Linked List
二元樹的右視圖 | Medium | LeetCode#199. Binary Tree Right Side View
所有 Root-Leaf 路徑總和 | Medium | LeetCode#129. Sum Root to Leaf Numbers
二元搜尋樹迭代器 | Medium | LeetCode#173. Binary Search Tree Iterator
計算完整二元術節點 | Easy | LeetCode#222. Count Complete Tree Nodes
二元樹路徑總和 | Easy | LeetCode#112. Path Sum
透過 Preorder Traversal 和 Inorder Traversal 建構二元樹 | Medium | LeetCode#105. Construct Binary Tree from Preorder and Inorder Traversal
二元樹各層的平均值 | Easy | LeetCode#637. Average of Levels in Binary Tree
對稱的二元樹 | Easy | LeetCode#101. Symmetric Tree