位逆置变换

将数组

int a[] = {0 , 1 , 2 , 3 , 4 , 5 , 6 , 7};

进行位逆置变换变为

{0 , 4 , 2 , 6 , 1 , 5 , 3 , 7};

变换前二进制表示为：

000 , 001 , 010 , 011 , 100 , 101 , 110 , 111

变换后：

000 , 100 , 010 , 110 , 001 , 101 , 011 , 111

代码如下：

#include <iostream>using namespace std;// the array size must be is 2 of pow// such as : 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7// binary express is :000 , 001 , 010 , 011 , 100 , 101 , 110 , 111// the reserve bit is : 000 , 100 , 010 , 110 , 001 , 101 , 011 , 111//                      0   , 4   , 2   , 6   , 1   , 5   , 3   , 7template<size_t N>void ReserveBit( int( &n )[N] ){    int size = log( N ) / log( 2 );    for( int index = 0; index < N; index++ )    {        int answer = 0;        int bit = 1;        for( int i = 0; i < size; i++ )        {            answer <<= 1;            if( n[index] & bit )            {                answer |= 1;            }            bit <<= 1;        }        n[index] = answer;    }}int main( void ){    int a[] = { 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 };    ReserveBit( a );    int size = sizeof( a ) / sizeof( a[0] );    for( int i = 0; i < size; i++ )    {        cout << i << ": " << a[i] << endl;    }    system( "pause" );    return 0;}

结果如下：