Repeated String Match

Description

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 <= 104
• 1 <= b.length <= 104
• a and b consist of lower-case English letters.

Solution(javascript)

/**
 * @param {string} A
 * @param {string} B
 * @return {number}
 */
const repeatedStringMatch = function (A, B) {
  let i = 1
  let current = A
  while (true) {
    if (current.indexOf(B) >= 0) {
      return i
    }
    if ((current.length > B.length * 2) && i > 2) {
      return -1
    }
    current += A
    i += 1
  }
}