686. Repeated String Match

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Problem

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

Constraints:

• $1<=a.length,b.length<={10}^4$
• a and b consist of lowercase English letters.

Code

class Solution {
    public int repeatedStringMatch(String a, String b) {
        int count = 0;
        String curr = "";

        while (curr.length() < b.length()) {
            curr += a;
            count++;
        }

        if(curr.contains(b)) return count;

        curr += a;
        count++;
        if(curr.contains(b)) return count;

        return -1;
    }
}