摘要：
Matt’s friend K.Bro is an ACMer. Yesterday, K.Bro learnt an algorithm: Bubble sort. Bubble sort will compare each pair of adjacent items and swap them 阅读全文
摘要：
XXX has an array of length n. XXX wants to know that, for a given w, what is the sum of the distinct elements’ number in all substrings of length w. F 阅读全文