Question

I need to find a highly optimized algo to sort an array consisting of only 0s n 1s.

My version of the solution is to count the no. of zeroes(say x) and ones(say y). Once you do that, place x zeroes in the array followed by y 1s. This makes it O(n).

Any algo that runs better than this??? I was asked this question in interview.

Answer 1

Since you have to examine each of n input elements, you can’t improve on O(n).

Also, since your algorithm requires O(1) memory, you can’t improve on that either (there’s nothing asymptotically better than O(1)).