Unique Length-3 Palindromic Subsequences 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 obt...

Number of Ways to Split Array You are given a 0-indexed integer array nums of length n. nums contains a valid split at index i if the following are true: The sum of the first i + 1 elements is ...

Count Vowel Strings in Ranges You are given a 0-indexed array of strings words and a 2D array of integers queries. Each query queries[i] = [li, ri] asks us to find the number of strings present ...

Maximum Score After Splitting a String Given a string s of zeros and ones, return the maximum score after splitting the string into two non-empty substrings (i.e. left substring and right substri...

Minimum Cost For Tickets You have planned some train traveling one year in advance. The days of the year in which you will travel are given as an integer array days. Each day is an integer from 1...

Count Ways To Build Good Strings Given the integers zero, one, low, and high, we can construct a string by starting with an empty string, and then at each step perform either of the following: A...

Number of Ways to Form a Target String Given a Dictionary You are given a list of strings of the same length words and a string target. Your task is to form target using the given words under th...

Maximum Sum of 3 Non-Overlapping Subarrays Given an integer array nums and an integer k, find three non-overlapping subarrays of length k with maximum sum and return them. Return the result as a...

Best Sightseeing Pair You are given an integer array values where values[i] represents the value of the ith sightseeing spot. Two sightseeing spots i and j have a distance j - i between them. Th...

Target Sum You are given an integer array nums and an integer target. You want to build an expression out of nums by adding one of the symbols ‘+’ and ‘-‘ before each integer in nums and then co...