Reverse Bits

Description:

Reverse bits of a given 32 bits unsigned integer.
For example, given input 43261596 (represented in binary as 00000010100101000001111010011100), return 964176192 (represented in binary as 00111001011110000010100101000000).

Follow up:

If this function is called many times, how would you optimize it?

Solution:

class Solution {
public:
	uint32_t reverseBits(uint32_t n) {
		n = (n & 0xffff0000) >> 16 | (n & 0x0000ffff) << 16;
		n = (n & 0xff00ff00) >> 8 | (n & 0x00ff00ff) << 8;
		n = (n & 0xf0f0f0f0) >> 4 | (n & 0x0f0f0f0f) << 4;
		n = (n & 0xcccccccc) >> 2 | (n & 0x33333333) << 2;
		n = (n & 0xaaaaaaaa) >> 1 | (n & 0x55555555) << 1;
		return n;
	}
};