摘要：
Q: Given a non-negative integer num, repeatedly add all its digits until the result has only one digit. For example: Given num = 38, the process is li 阅读全文
摘要：
Q: You are playing the following Nim Game with your friend: There is a heap of stones on the table, each time one of you take turns to remove 1 to 3 s 阅读全文