README.md

1278. Palindrome Partitioning III

You are given a string s containing lowercase letters and an integer k. You need to :

• First, change some characters of s to other lowercase English letters.
• Then divide s into k non-empty disjoint substrings such that each substring is a palindrome.

Return the minimal number of characters that you need to change to divide the string.

Example 1:

Input: s = "abc", k = 2
Output: 1
Explanation: You can split the string into "ab" and "c", and change 1 character in "ab" to make it palindrome.

Example 2:

Input: s = "aabbc", k = 3
Output: 0
Explanation: You can split the string into "aa", "bb" and "c", all of them are palindrome.

Example 3:

Input: s = "leetcode", k = 8
Output: 0

Constraints:

• 1 <= k <= s.length <= 100.
• s only contains lowercase English letters.

Solutions (Python)

1. Solution

from functools import cache


class Solution:
    def palindromePartition(self, s: str, k: int) -> int:
        @cache
        def palindromeChange(i: int, j: int) -> int:
            if i >= j:
                return 0

            return palindromeChange(i + 1, j - 1) + (s[i] != s[j])

        @cache
        def subPartition(i: int, k: int) -> int:
            if k == 1:
                return palindromeChange(i, len(s) - 1)

            return min(palindromeChange(i, j) + subPartition(j + 1, k - 1) for j in range(i, len(s) - k + 1))

        return subPartition(0, k)