• Question
• Solution

Question

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

Result: Accepted Time: 8 ms

Here should be some explanations.

class Solution {
public:
    uint32_t reverseBits(uint32_t n) {
        uint32_t ans = 0;
        int i=32;
        while(i--)
        {
            ans = (ans << 1) | (n&1);
            n >>= 1;
        }
        return ans;
    }
};

Complexity Analytics

• Time Complexity: $O(log(n))$
• Space Complexity: $O(1)$