摘要：
Question Given a linked list, swap every two adjacent nodes and return its head. For example, Given 1 2 3 4, you should return the list as 2 1 4 3. Yo 阅读全文
摘要：
Question There are n bulbs that are initially off. You first turn on all the bulbs. Then, you turn off every second bulb. On the third round, you togg 阅读全文