last of size 30 (since the maximum number in nums can be up to 2^30) to store the last index at which each bit is set.nums array in reverse, updating the last array for each bit that is set in the current number.i, find the maximum value in the last array, which represents the farthest index we need to include to get the maximum bitwise OR.i is the difference between the maximum value in the last array and i, plus one.