Leetcode 796 Rotate String

Given two strings s and goal, return true if and only if s can become goal after some number of shifts on s.

A shift on s consists of moving the leftmost character of s to the rightmost position.

• For example, if s = “abcde”, then it will be “bcdea” after one shift.

Input: s = "abcde", goal = "cdeab"
Output: true

Input: s = "abcde", goal = "abced"
Output: false

• All rotations of A are contained in A+A. Thus, we can simply check whether B is a substring of A+A. We also need to check A.length == B.length, otherwise we will fail cases like A = “a”, B = “aa”.

class Solution(object):
    def rotateString(self, A, B):
        return len(A) == len(B) and B in A+A