[CSES][Sorting and Searching] Array Division

https://cses.fi/problemset/task/1085 In this problem, we are asked to split an array of positive integers into k blocks while minimizing the maximal sum of a block. we can achieve this with binary searching through all possible maximal sums in O(log(n)) and checking for validity in O(n) for a total complexity of O(n*log(n))