Reverse Bits

最新推荐文章于 2024-01-19 11:13:02 发布

原创最新推荐文章于 2024-01-19 11:13:02 发布 · 322 阅读

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v1:

class Solution {
public:
    uint32_t reverseBits(uint32_t n) {
        uint32_t res = 0;
        uint32_t r = 1;
        for (int i =0; i< 32; i++) {
            uint32_t temp = n & r;
            if (i < 16) res |= (temp << (31 - 2*i));
            else res |= (temp >> (2*i - 31));
            r = r << 1;
        }
        return res;
    }
};

v2:

class Solution {
public:
    uint32_t reverseBits(uint32_t n) {
        uint32_t res = 0;
        uint32_t r = 1;
        for (int i =0; i< 32; i++) {
            uint32_t temp = n & r;
            if (temp) {
                res |= (temp << (31 - i));
            }
            if (!(n = n >> 1)) break;
        }
        return res;
    }
};

v3:

class Solution {
public:
    uint32_t reverseBits(uint32_t n) {
        uint32_t res = 0;
        for (int i = 0; i < 4; i++) {
            uint32_t t8 = (n >> (i * 8)) & 0xFF;
            uint32_t rt8 = 0;
            for (int j = 0; j < 4; j++) {
                uint32_t t2 = 0, t1 = 0;
                t2 = (t8 >> (j * 2) & 0x3);
                t1 |= (t2 & 0x1) << 1;
                t2 = (t2 >> 1) | t1;
                rt8 |= (t2 << (2 * (3 - j)));
            }
            res |= (rt8 << (8 * (3 - i)));
        }
        return res;
    }
};