Year

2025 archive

A year-sized slice of the daily archive, ordered newest first.

365 entries

365 entries from 2025.

04.01.2025

medium

1930. Unique Length-3 Palindromic Subsequences

Count palindromes of length 3

building a HashSet can be slower then just checking for contains 26 times using unordered_set to count unique characters in the substring finding the span between first and last occurrences of a character counting unique characters within the substring defined by character occurrences manipulating and analyzing string content implicit use of string as an array of characters