Given a 0-indexed string word and a character ch, reverse the segment of word that starts at index 0 and ends at the index of the first occurrence of ch (inclusive). If the character ch does not exist

You are given an m x n binary matrix matrix. You can choose any number of columns in the matrix and flip every cell in that column (i.e., Change the value of the cell from 0 to 1 or vice versa). Retur

You are given the array paths, where paths[i] = [cityAi, cityBi] means there exists a direct path going from cityAi to cityBi. Return the destination city, that is, the city without any path outg

You are given a 0-indexed string s of even length n. The string consists of exactly n / 2 opening brackets ‘[‘ and n / 2 closing brackets ‘]’. A string is called balanced if and only if:It i

Given an array of positive integers arr (not necessarily distinct), return thelexicographically largest permutation that is smaller than arr, that can be made with exactly one swap. If it cannot be do

You are given a 0-indexed integer array piles, where piles[i] represents the number of stones in the ith pile, and an integer k. You should apply the following operation exactly k times:Choose any pil

The Tribonacci sequence Tn is defined as follows:T0 = 0, T1 = 1, T2 = 1, and Tn+3 = Tn + Tn+1 + Tn+2 for n >= 0.Given n, return the value of Tn. Example 1:Input: n = 4

order and str are strings composed of lowercase letters. In order, no letter occurs more than once. order was sorted in some custom order previously. We want to permute the characters of str so that t

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 counte

You are given two m x n binary matrices grid1 and grid2 containing only 0’s (representing water) and 1’s (representing land). An island is a group of 1’s connected 4-directionally (horizontal or verti