Trace n = 5.
bits[0] = 0 (base case).
bits[1] = bits[1 >> 1] + (1 & 1) = bits[0] + 1 = 0 + 1 = 1. bits[2] = bits[2 >> 1] + (2 & 1) = bits[1] + 0 = 1 + 0 = 1. bits[3] = bits[3 >> 1] + (3 & 1) = bits[1] + 1 = 1 + 1 = 2. bits[4] = bits[4 >> 1] + (4 & 1) = bits[2] + 0 = 1 + 0 = 1. bits[5] = bits[5 >> 1] + (5 & 1) = bits[2] + 1 = 1 + 1 = 2.
Answer: [0, 1, 1, 2, 1, 2].
time, space for the output array.