Package g0701_0800.s0730_count_different_palindromic_subsequences

Class Solution

java.lang.Object

g0701_0800.s0730_count_different_palindromic_subsequences.Solution

public class Solution
extends Object

730 - Count Different Palindromic Subsequences\. Hard Given a string s, return _the number of different non-empty palindromic subsequences in_ `s`. Since the answer may be very large, return it **modulo** 109 + 7. A subsequence of a string is obtained by deleting zero or more characters from the string. A sequence is palindromic if it is equal to the sequence reversed. Two sequences a1, a2, ... and b1, b2, ... are different if there is some `i` for which ai != bi. **Example 1:** **Input:** s = "bccb" **Output:** 6 **Explanation:** The 6 different non-empty palindromic subsequences are 'b', 'c', 'bb', 'cc', 'bcb', 'bccb'. Note that 'bcb' is counted only once, even though it occurs twice. **Example 2:** **Input:** s = "abcdabcdabcdabcdabcdabcdabcdabcddcbadcbadcbadcbadcbadcbadcbadcba" **Output:** 104860361 **Explanation:** There are 3104860382 different non-empty palindromic subsequences, which is 104860361 modulo 10⁹ + 7. **Constraints:** * `1 <= s.length <= 1000` * `s[i]` is either `'a'`, `'b'`, `'c'`, or `'d'`.

Constructor Summary

Constructors

Constructor	Description
Solution()

Method Summary

Modifier and Type	Method	Description
int	countPalindromicSubsequences(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

countPalindromicSubsequences

public int countPalindromicSubsequences(String s)