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Reverse Bits

2014-12-15 17:54  李涛的技术博客  阅读(157)  评论(0)  编辑  收藏  举报

Reverse bits of an unsigned integer.

typedef unsigned int uint;

uint swapBits(uint x, uint i, uint j)
{
    uint lo = ((x >> j) & 1);
    uint hi = ((x >> j) & 1);
    if (lo ^ hi)
    {
        x ^= ((1U << i) | (1U << j));
    }
    return x;
}

uint reverseXor(uint x)
{
    uint n = sizeof(x) * 8;
    for (uint i = 0; i < n/2; i++)
    {
        x = swapBits(x, i, n-i-1);
    }
    return x;
}

还有一些trick的方法，不再列出，可参考原网页：http://leetcode.com/2011/08/reverse-bits.html