O(n) algorithm to find the median of a collection of numbers

Question

Problem: input is a (not necessarily sorted) sequence S = k1, k2, ..., kn of n arbitrary numbers. Consider the collection C of n² numbers of the form min{ki,kj}, for 1 <=

Answer 1

Wikipedia has a good article on Selection algorithms. If you are using C++, the STL includes a nth_element() algorithm with linear time on average.