This time the pattern is triples, not pairs — every value in the array repeats exactly three times except for one lone holdout that shows up just once. Identify it. Plain XOR can't help here, since XOR-ing a value with itself three times just leaves the value unchanged (it doesn't cancel like it does for pairs). Instead, look at each of the 32 bit positions on its own: a value repeated three times always contributes a multiple of 3 to that position's total, so any position whose total isn't a multiple of 3 must be getting its extra contribution from the one unpaired value.