上課手寫的

實測：

#include <stdio.h>
#include <time.h>

int count = 0;

int search(unsigned char A, unsigned char B, unsigned char C)
{
    if(B!=255)
    {    
    unsigned char D = ~(A|B|C);
     while(D)
     {
        unsigned char bit = D & (-D);
        D ^= bit;
        search((A|bit)<<1
 
, B|bit, (C|bit)>>1);
     }
    }
    else
    count ++;
   return 0;
}


int main(){
    time_t tm;
    tm =time(0);
    search(0, 0, 0);
    printf("count:%d\ntime:%ld\n", count,time(0)-tm);
    return 0;
}

結果：