You have three identical light bulbs in a windowless room, each connected to one of three switches outside. All bulbs are currently off. You can flip any of the switches only once before entering the room to identify which switch controls which bulb. How can you determine the correct switch for each bulb?

Write a program to sort a stack in ascending order, with the largest items on top. You may use only one additional stack for temporary storage, and you cannot use any other data structure (such as an array). The stack should support the following operations: push, pop, peek, and isEmpty

Write a method to sort an array of strings, grouping anagrams together

Write a function to solve the job scheduling problem that maximizes profit

Write a function to find the longest substring without repeating characters in a given string

Write a function to execute an inorder traversal of a binary tree

Write a function to determine the longest univalue path in a binary tree

Write a function to determine if a given string is a valid palindrome

Write a function to determine if a given string is a permutation of a palindrome, where a palindrome reads the same forwards and backwards

Write a function to calculate the path sum in a binary tree

Write a function to calculate the number of distinct ways to construct a specified string

Write a function to calculate the maximum path sum in a binary tree

Write a function to calculate the maximum area of an island in a 2D grid

Write a function to calculate the distance between two nodes in a binary tree

Write a function that calculates the sum of all nodes in a binary tree that have an even-valued grandparent