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摘要： 题目： Assume you have a method isSubstring which checks if one word is a substring of another. Given two strings, s1 and s2, write code to check if s2 is a rotation of s1 using only one call to isSubstring (e.g., "waterbottle" is a rotation of "erbottlewat").解析： 这道题一开始做的时候想法比较笨，一开始 阅读全文