public class Solution
extends Object
686 - Repeated String Match\.
Medium
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 "ab**cdabcdab**cd", b is a substring of it.
**Example 2:**
**Input:** a = "a", b = "aa"
**Output:** 2
**Constraints:**
* 1 <= a.length, b.length <= 104
* `a` and `b` consist of lowercase English letters.