3137 - Minimum Number of Operations to Make Word K-Periodic.

Medium

You are given a string word of size n, and an integer k such that k divides n.

In one operation, you can pick any two indices i and j, that are divisible by k, then replace the substring of length k starting at i with the substring of length k starting at j. That is, replace the substring word[i..i + k - 1] with the substring word[j..j + k - 1].

Return the minimum number of operations required to make word k-periodic.

We say that word is k-periodic if there is some string s of length k such that word can be obtained by concatenating s an arbitrary number of times. For example, if word == “ababab”, then word is 2-periodic for s = "ab".

Example 1:

Input: word = "leetcodeleet", k = 4

Output: 1

Explanation:

We can obtain a 4-periodic string by picking i = 4 and j = 0. After this operation, word becomes equal to "leetleetleet".

Example 2:

Input: word = "leetcoleet", k = 2

Output: 3

Explanation:

We can obtain a 2-periodic string by applying the operations in the table below.

i  j  word
0  2  etetcoleet
4  0  etetetleet
6  0  etetetetet

Constraints:

• <code>1 <= n == word.length <= 10⁵</code>

• 1 <= k <= word.length

• k divides word.length.

• word consists only of lowercase English letters.