Given an integer array nums and an integer k, return the k most frequent elements. You may return the answer in any order.

Given an array of strings strs, group the anagrams together. You can return the answer in any order.

Given two strings s and t, return true if t is an anagram of s, and false otherwise.

Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.

Given an integer array nums, return true if any value appears at least twice in the array, and return false if every element is distinct.