Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string […]

Given an array nums of n integers, return an array of all the unique quadruplets [nums[a], nums[b], nums[c], nums[d]] such

Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent. Return the

Given an integer array nums of length n and an integer target, find three integers at distinct indices in nums

Given an integer array nums, return all the triplets [nums[i], nums[j], nums[k]] such that i != j, i != k,

Write a function to find the longest common prefix string amongst an array of strings. If there is no common

Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. Symbol Value I 1 V

Seven different symbols represent Roman numerals with the following values: Symbol Value I 1 V 5 X 10 L 50

You are given an integer array height of length n. There are n vertical lines drawn such that the two

Given an input string s and a pattern p, implement regular expression matching with support for '.' and '*' where: '.'

Given an integer x, return true if x is a palindrome, and false otherwise.   Example 1: Input: x =