《Cracking the Coding Interview》——第5章：位操作——题目6

2014-03-19 06:24

题目：将一个整数的奇偶二进制位交换，(0, 1) (2, 3) ...

解法：使用掩码来进行快速交换，定义掩码为'0101...'和‘1010...’。

代码：

 // 5.6 Swap odd and even bits in an integer.
 #include <cstdio>
 using namespace std;

 unsigned int swapBits(unsigned int n)
 {
     static const unsigned int mask[] = {0x55555555, 0xaaaaaaaa};

     return ((n & mask[]) << ) + ((n & mask[]) >> );
 }

 int main()
 {
     unsigned int n;

     while (scanf("%u", &n) == ) {
         printf("%u\n", swapBits(n));
     }

     return ;
 }