2430 - Maximum Deletions on a String\.

Hard

You are given a string s consisting of only lowercase English letters. In one operation, you can:

• Delete the entire string s, or

• Delete the first i letters of s if the first i letters of s are equal to the following i letters in s, for any i in the range 1 <= i <= s.length / 2.

For example, if s = "ababc", then in one operation, you could delete the first two letters of s to get "abc", since the first two letters of s and the following two letters of s are both equal to "ab".

Return the maximum number of operations needed to delete all of s.

Example 1:

Input: s = "abcabcdabc"

Output: 2

Explanation:

• Delete the first 3 letters ("abc") since the next 3 letters are equal. Now, s = "abcdabc".

• Delete all the letters.

We used 2 operations so return 2. It can be proven that 2 is the maximum number of operations needed.

Note that in the second operation we cannot delete "abc" again because the next occurrence of "abc" does not happen in the next 3 letters.

Example 2:

Input: s = "aaabaab"

Output: 4

Explanation:

• Delete the first letter ("a") since the next letter is equal. Now, s = "aabaab".

• Delete the first 3 letters ("aab") since the next 3 letters are equal. Now, s = "aab".

• Delete the first letter ("a") since the next letter is equal. Now, s = "ab".

• Delete all the letters.

We used 4 operations so return 4. It can be proven that 4 is the maximum number of operations needed.

Example 3:

Input: s = "aaaaa"

Output: 5

Explanation: In each operation, we can delete the first letter of s.

Constraints:

• 1 <= s.length <= 4000

• s consists only of lowercase English letters.