LeetCode 190. Reverse Bits

题目描述:

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).

翻转一个32位整数的每一个位.

class Solution {
public:
    uint32_t reverseBits(uint32_t n) {
        for(int i = 0; i < 16; i++){
            swapIntBit(n, i);
        }
        return n;
    }

    void swapIntBit(uint32_t &n, int i){
        uint32_t b1 = n & (1 << i);
        uint32_t b2 = n & (((unsigned int)0x80000000) >> i);
        n &= ~(1 << i);
        n &= ~(((unsigned int)0x80000000) >> i);
        n |= b1 << (31 - i * 2);
        n |= b2 >> (31 - i * 2);
    }
};