Given an array of integers arr, return true if the number of occurrences of each value in the array is unique, or false otherwise. Example 1:Input: arr = [1,2,2,1,1,3]Output: trueExplanation: The

You are given a string s consisting only of the characters ‘0’ and ‘1’. In one operation, you can change any ‘0’ to ‘1’ or vice versa. The string is called alternating if no two adjacent characters ar

You are given an integer array matches where matches[i] = [winneri, loseri] indicates that the player winneri defeated player loseri in a match. Return a list answer of size 2 where:answer[0] is

You are given two strings word1 and word2. Merge the strings by adding letters in alternating order, starting with word1. If a string is longer than the other, append the additional letters onto the e

The school cafeteria offers circular and square sandwiches at lunch break, referred to by numbers 0 and 1 respectively. All students stand in a queue. Each student either prefers square or circular sa

An integer array original is transformed into a doubled array changed by appending twice the value of every element in original, and then randomly shuffling the resulting array. Given an array changed

You are given an array nums of non-negative integers. nums is considered special if there exists a number x such that there are exactly x numbers in nums that are greater than or equal to x. Notice th

A bus has n stops numbered from 0 to n - 1 that form a circle. We know the distance between all pairs of neighboring stops where distance[i] is the distance between the stops number i and (i + 1) % n.

Let’s define a function countUniqueChars(s) that returns the number of unique characters in s. For example, calling countUniqueChars(s) if s = “LEETCODE” then “L”, “T”, “C”, “O”, “D” are the uniq

You are implementing a program to use as your calendar. We can add a new event if adding the event will not cause a double booking. A double booking happens when two events have some non-empty interse