[leetcode] Reverse Bits


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 as00111001011110000010100101000000).

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

Related problem: Reverse Integer

Credits:
Special thanks to @ts for adding this problem and creating all test cases.

Reverse the bits sequence.

class Solution {
public:
    uint32_t reverseBits(uint32_t n) {
        uint32_t ans = 0;
        for(size_t i = 0; i < 32; i++){
            uint32_t bit = ((0x00000001 << i) & n) >> i;
            ans = ans | (bit << (31 - i));
        }
        return ans;
    }
};

Use lookup table to speed up this program.

 

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