686. Repeated String Match

Given two strings a and b, return the minimum number of times you should repeat string a so that string b is a substring of it. If it is impossible for b​​​​​​ to be a substring of a after repeating it, return -1. Notice: string "abc" repeated 0 times is "", repeated 1 time is "abc" and repeated 2 times is "abcabc". Example 1: Input: a = "abcd", b = "cdabcdab" Output: 3 Explanation: We return