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 ( i.e., “waterbottle” is a rotation of “erbottlewat”).
思路：s1连接s1构成新字符串，然后判断s2是否是s1s1的子串即可。
public static boolean isRotation(String s1, String s2) { int len = s1.length(); /* check that s1 and s2 are equal length and not empty */ if (len == s2.length() && len > 0) { /* concatenate s1 and s1 within new buffer */ String s1s1 = s1 + s1; return isSubstring(s1s1, s2); } return false; }
Cracking the Coding Interview Q1.8,布布扣,bubuko.com
Cracking the Coding Interview Q1.8
原文：http://www.cnblogs.com/jdflyfly/p/3830595.html