g1301_1400.s1332_remove_palindromic_subsequences.Solution Maven / Gradle / Ivy

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package g1301_1400.s1332_remove_palindromic_subsequences;

// #Easy #String #Two_Pointers #2022_03_19_Time_0_ms_(100.00%)_Space_39.9_MB_(78.40%)

/**
 * 1332 - Remove Palindromic Subsequences\.
 *
 * 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'`.
**/
public class Solution {
    public int removePalindromeSub(String s) {
        if (s.isEmpty()) {
            return 0;
        }
        if (s.equals((new StringBuilder(s)).reverse().toString())) {
            return 1;
        }
        return 2;
    }
}