Problem
The radix sort algorithm sorts an array of n integers with d digits, using ten auxiliary arrays. First place each value v into the auxiliary array whose index corresponds to the last digit of v. Then move all values back into the original array, preserving their order. Repeat the process, now using the next-to-last (tens) digit, then the hundreds digit, and so on. What is the big-Oh time of this algorithm in terms of n and d? When is this algorithm preferable to merge sort?