RemovePalindromicSubsequences1332.kt

package easy

/**
 * You are given a string s consisting only of letters 'a' and 'b'. In a single step you can remove one palindromic subsequence from s.

Return the minimum number of steps to make the given string empty.

A string is a subsequence of a given string if it is generated by deleting some characters of a given string without changing its order. Note that a subsequence does not necessarily need to be contiguous.

A string is called palindrome if is one that reads the same backward as well as forward.



Example 1:

Input: s = "ababa"
Output: 1
Explanation: s is already a palindrome, so its entirety can be removed in a single step.
Example 2:

Input: s = "abb"
Output: 2
Explanation: "abb" -> "bb" -> "".
Remove palindromic subsequence "a" then "bb".
Example 3:

Input: s = "baabb"
Output: 2
Explanation: "baabb" -> "b" -> "".
Remove palindromic subsequence "baab" then "b".


Constraints:

1 <= s.length <= 1000
s[i] is either 'a' or 'b'.
 */
fun removePalindromeSub(s: String): Int {
    return when {
        s.isEmpty() -> 0
        s.isPalindrome() -> 1
        else -> 2
    }

}

fun String.isPalindrome(): Boolean {
    return this == this.reversed()
}