Reverse the bits of a 32-bit unsigned integer.
With n = 00000010100101000001111010011100 (binary):
- Reversed:
00111001011110000010100101000000. - Input: . Output: .
With n = 11111111111111111111111111111101:
- Reversed:
10111111111111111111111111111111. - Input: . Output: .
Constraints: Input is a 32-bit unsigned integer.