Given two integers n and k, construct a list answer that contains n different positive integers ranging from 1 to n and obeys the following requirement: Suppose this list is answer = [a1, a2, a3, ... , an], then the list [|a1 - a2|, |a2 - a3|, |a3 - a4|, ... , |an-1 - an|] has exactly k distinct integers. Return the list answer. If there multiple valid answers, return any of them.