摘要：
Valid Number (H) 题目 Validate if a given string can be interpreted as a decimal number. Some examples: "0" ⇒ true " 0.1 " ⇒ true "abc" ⇒ false "1 a" ⇒ 阅读全文
摘要：
Flatten Binary Tree to Linked List (M) 题目 Given a binary tree, flatten it to a linked list in-place. For example, given the following tree: 1 / \ 2 5 阅读全文