Determine if two strings are anagrams of each other, meaning they contain the same characters in a different order. You need to check if one string can be rearranged to form the other.

You're given the costs of candies and a discount: for every three candies you buy, the cheapest one is free. Find the minimum total cost to buy all the candies.

Find the longest string that is a prefix of all strings in a given array. If no common prefix exists, return an empty string.