Given an array where each element represents the required size of the group for each person, group the people accordingly and return the groups. Each person must be in exactly one group.
Given an array of integers and a threshold, find the smallest divisor such that the sum of the division results (rounded up) is less than or equal to the threshold.
Design a CombinationIterator class that generates all combinations of a specified length from a sorted string of distinct lowercase English letters, and allows iterating through them in lexicographical order.
You are given a matrix of integers and a threshold. Your goal is to find the maximum side length of a square where the sum of the elements inside the square is less than or equal to the threshold.