Info why it doesn't work: the smallest array for which it fails has 3 elements. When you start with a sorted array, iterate through each element and move it to one of the 3 positions with equal probability, there are 3³ = 27 possible move sequences, each with probability 1/27, but only 3! = 6 possible outcomes (permutations of the array). Because 6 doesn't divide 27, there must be some outcomes that are generated by more move sequences than others and hence occur more often.