LeetCode : Reverse Bits

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?

Related problem: Reverse Integer

class Solution {
public:
    uint32_t reverseBits(uint32_t n) {
        uint32_t num = 0;
        for(int i=0;i<32;++i)
        {
            num = (num<<1)+(n>>i&1);
        }
        return num;
    }
};