摘要：
DescriptionGiven two strings a and b we define a*b to be their concatenation. For example, if a = "abc" and b = "def" then a*b = "abcdef". If we think... 阅读全文
摘要：
DescriptionFor each prefix of a given string S with N characters (each character has an ASCII code between 97 and 126, inclusive), we want to know whe... 阅读全文