#686 - Repeated String Match

Easy • View on LeetCode • View on GitHub

Problem Description

Given two strings A and B, find the minimum number of times A has to be repeated such that B is a substring of it. If no such solution, return -1.

For example, with A = "abcd" and B = "cdabcdab".

Return 3, because by repeating A three times (“abcdabcdabcd”), B is a substring of it; and B is not a substring of A repeated two times ("abcdabcd").

Solution

/**
 * @param {string} A
 * @param {string} B
 * @return {number}
 */
var repeatedStringMatch = function(A, B) {
  const length = Math.ceil(B.length / A.length);
  if (A.repeat(length).includes(B)) return length;
  if ((A.repeat(length) + A).includes(B)) return length + 1;
  return -1;
};