Reverse Bits

• Time : $O(logA)$
• Space : $O(1)$

c++

unsigned int Solution::reverse(unsigned int A) {
    unsigned int res = 0;
    for(int i = 0; i < 32; i++) {
        if(A & (1<<i)) res |= 1<<(32-i-1);
    }
    return res;
}