Rotate String

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

A rotation moves the leftmost character of the string to the rightmost end. For example, rotating "abcde" once produces "bcdea".

An equivalent way to think about the problem is: goal is a rotation of s if the two strings have the same length and goal appears inside s + s.

Input / output

• Input: s: string, goal: string
• Output: boolean

Constraints

• 1 <= s.length, goal.length <= 100
• s and goal consist of lowercase English letters.

Follow-up

How would you check whether goal is a rotation of s without explicitly building the doubled string s + s?