leetcode-96 - Unique Binary Search Trees
動機 當成range，就可以去二分了 ...
Binary Tree
leetcode-337 - House Robber III
動機 樹型dp 用sum(list of list,[])去攤平一層 ...
leetcode-437 - Path Sum III
動機 原來是prefix sum的靈壓!! ...
leetcode-236 - Lowest Common Ancestor of a Binary Tree
動機 我忘了localty ...
leetcode-94 - Binary Tree Inorder Traversal
動機 中序的英文是inorder，一開始寫以為是前序 ...
leetcode-101 - Symmetric Tree
動機 複習bfs ...
leetcode-235 - Lowest Common Ancestor of a Binary Search Tree
動機 善用binary search tree，所以才是easy ...
leetcode-124 - Binary Tree Maximum Path Sum
動機 十分有趣 ...
leetcode-572 - Subtree of Another Tree
動機 老實地分成兩個dfs ...
leetcode-98 - Validate Binary Search Tree
動機 當初還想著怎麼看node… ...