Given an integer array nums and an integer k, your task is to determine if it is possible to divide this array into k non-empty subsets such that each subset has an equal sum.
You are given a sorted array of integers and a target value. Your task is to search for the target in the array. If the target exists, return its index. If it does not exist, return -1. You must achieve a time complexity of O(log n).
Design a custom HashSet without using any built-in hash table libraries. Implement the MyHashSet class with methods to add, remove, and check the existence of a value.
Given an array of integers nums and an integer k, return the number of contiguous subarrays where the product of all the elements in the subarray is strictly less than k.
You are given an array prices where prices[i] represents the price of a stock on the i-th day, and an integer fee that represents a transaction fee for each transaction. The task is to calculate the maximum profit you can achieve. You may complete as many transactions as you like, but you need to pay the transaction fee for each transaction.
