When determining the h-index, it is obvious that we need to observe the papers with more citations. Therefore, we first sort the numbers by size, starting with the largest. We iterate over this array respectively (index ~K = 1, 2, 3, \dots~) and if the ~K^\text{th}~ element is larger than or equal to ~K~, this means that ~K~ is a potential h-index (because the scientist has at least ~K~ papers with a citation score larger than or equal to ~K~). The task comes down to finding the largest such ~K~, which is easily solved by storing the solution in an auxiliary variable and updating it while iterating the array.