Given a positive integer, output its complement number. The complement strategy is to flip the bits of its binary representation.
The given integer is guaranteed to fit within the range of a 32-bit signed integer. You could assume no leading zero bit in the integer’s binary representation.
Explanation: The binary representation of 5 is 101 (no leading zero bits), and its complement is 010. So you need to output 2.
Explanation: The binary representation of 1 is 1 (no leading zero bits), and its complement is 0. So you need to output 0.
Time: O(N) where N is the number of bits in num
Space: O(N) where N is the number of bits in num
In python, to operate on the bit-level there must be an
O(log N) call to
bin() which creates a binary string representation of num. Notice the usage of [2:] which strips out the leading ‘b’ character for binary string. After that, you’re just building up a binary string to represent each flipped bit and converting it to an integer by specifiying base 2.