Given two integer arrays nums1 and nums2, return an array of their intersection. Each element in the result must be unique, and you may return the result in any order.
Design a data structure that supports three operations: insert, remove, and getRandom. The insert operation adds an element to the set if it is not already present. The remove operation removes an element from the set if it exists. The getRandom operation returns a random element from the set, with each element having an equal probability of being selected.
Given two strings ransomNote and magazine, return true if ransomNote can be constructed by using the letters from magazine. Each letter in magazine can only be used once.
