if someone is struggling with understanding problem-B, the key observation is there should be a number which can be completely absorbed into rest of the numbers. i.e. there is an a[i] whose set bits are [x1, x2, x3] and aj has set bits [x1, x3] and a[k] (k!=j && k!=i) has set bits [x2, x4, x5] then seq-a would be all elements in array and seq-b would be all elements in array except a[i] since those set bits already exist via rest of the elements