Algorithm: efficient way to remove duplicate integers from an array

Question

I got this problem from an interview with Microsoft.

Given an array of random integers, write an algorithm in C that removes duplicated numbers an

Answer 1

An array should obviously be "traversed" right-to-left to avoid unneccessary copying of values back and forth.

If you have unlimited memory, you can allocate a bit array for sizeof(type-of-element-in-array) / 8 bytes to have each bit signify whether you've already encountered corresponding value or not.

If you don't, I can't think of anything better than traversing an array and comparing each value with values that follow it and then if duplicate is found, remove these values altogether. This is somewhere near O(n^2) (or O((n^2-n)/2)).

IBM has an article on kinda close subject.