Leetcode: Repeated String Match

Repeated String Match



Similar Problems:


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”).

Note:
The length of A and B will be between 1 and 10000.

Github: code.dennyzhang.com

Credits To: leetcode.com

Leave me comments, if you have better ways to solve.


## Blog link: https://code.dennyzhang.com/repeated-string-match
## Basic Ideas: Consider lengths of A and B are len_a, len_b
##              Let's say a match exists. k = len_b/len_a
##              Then we need to repeat A either k times, k+1 times or k+2 times
## Complexity: Time O(m+n), Space O(n)
class Solution:
    def repeatedStringMatch(self, A, B):
        """
        :type A: str
        :type B: str
        :rtype: int
        """
        lenA, lenB = len(A), len(B)
        times = int(lenB/lenA)
        C = A*times
        if B in C: return times
        if B in C+A: return times+1
        if B in C+A+A: return times+2
        return -1
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