3 sequential numbers

Alright geniuses, if you think your programming ability is up to par, lets see you solve this:

Write an algorithm which in O(n) time finds 3 indices i, j, and k such that i < j < k and array[i] < array[j] < array[k].

>>20
As an extension of that problem, and what I think >>18 was hinting at, is that it fails with intermediate large values like in [1, 999, 2, 3]