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 3 because by repeating a three times "abcdabcdabcd", b is a substring of it.
Example 2:
Input: a = "a", b = "aa" Output: 2
Example 3:
Input: a = "a", b = "a" Output: 1
Example 4:
Input: a = "abc", b = "wxyz" Output: -1
Constraints:
1 <= a.length <= 1041 <= b.length <= 104aandbconsist of lower-case English letters.