796. Rotate String

We are given two strings, A and B.

A shift on A consists of taking string A and moving the leftmost character to the rightmost position. For example, if A = 'abcde', then it will be 'bcdea' after one shift on A. Return True if and only if A can become B after some number of shifts on A.

Example 1:
Input: A = 'abcde', B = 'cdeab'
Output: true

Example 2:
Input: A = 'abcde', B = 'abced'
Output: false

Note:

• A and B will have length at most 100.

判断字符串B能否通过字符串A旋转得到，程序如下所示：

class Solution {
    public boolean rotateString(String A, String B) {
        String s = A+A;
        return B.length() == A.length() && s.indexOf(B) != -1;
    }
}