摘要：
We are given N different types of stickers. Each sticker has a lowercase English word on it. You would like to spell out the given target string by cu 阅读全文
摘要：
Suppose you have N integers from 1 to N. We define a beautiful arrangement as an array that is constructed by these N numbers successfully if one of t 阅读全文
摘要：
A binary watch has 4 LEDs on the top which represent the hours (0-11), and the 6 LEDs on the bottom represent the minutes (0-59). Each LED represents 阅读全文