It's "obvious" (in a somewhat unreasonable sense of that word) that this can't give a truly random permutation of the elements of the array. Since the only rand

It's "obvious" (in a somewhat unreasonable sense of that word) that this can't give a truly random permutation of the elements of the array. Since the only randomness comes from coin-flips, the probability of any particular outcome must be a rational number whose denominator is a power of 2. But there are n! permutations of n objects, and for n > 2 this isn't a power of 2, so they can't all be being selected with equal probability.