Package g1901_2000.s1930_unique_length_3_palindromic_subsequences

Class Solution

java.lang.Object

g1901_2000.s1930_unique_length_3_palindromic_subsequences.Solution

public class Solution
extends Object

1930 - Unique Length-3 Palindromic Subsequences\. Medium Given a string `s`, return _the number of **unique palindromes of length three** that are a **subsequence** of_ `s`. Note that even if there are multiple ways to obtain the same subsequence, it is still only counted **once**. A **palindrome** is a string that reads the same forwards and backwards. A **subsequence** of a string is a new string generated from the original string with some characters (can be none) deleted without changing the relative order of the remaining characters. * For example, `"ace"` is a subsequence of `"abcde"`. **Example 1:** **Input:** s = "aabca" **Output:** 3 **Explanation:** The 3 palindromic subsequences of length 3 are: - "aba" (subsequence of "aabca") - "aaa" (subsequence of "aabca") - "aca" (subsequence of "aabca") **Example 2:** **Input:** s = "adc" **Output:** 0 **Explanation:** There are no palindromic subsequences of length 3 in "adc". **Example 3:** **Input:** s = "bbcbaba" **Output:** 4 **Explanation:** The 4 palindromic subsequences of length 3 are: - "bbb" (subsequence of "bbcbaba") - "bcb" (subsequence of "bbcbaba") - "bab" (subsequence of "bbcbaba") - "aba" (subsequence of "bbcbaba") **Constraints:** * 3 <= s.length <= 105 * `s` consists of only lowercase English letters.

Constructor Summary

Constructors

Constructor	Description
Solution()

Method Summary

Modifier and Type	Method	Description
int	countPalindromicSubsequence(String s)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

Solution

public Solution()

Method Details

countPalindromicSubsequence

public int countPalindromicSubsequence(String s)