Shuffle elements of an array/n numbers uniformly randomly. Possibley in expected O(n) time

Question

Is it possible to shuffle elements of an n-sized array uniformly, i.e. the probability of any of the n! combinations occurring is the same, in expected O(n) tim

Answer 1

For each array position:

Select a random number from current position to end of array

Swap current position with random position

That should give you O(n) without the challenge of finding an unused array position. This assumes you can use an in-place swap and that you don't have to create a new array.