[编程之美]中国象棋将帅问题

熟悉位操作符和位的存储方法

#include <stdio.h>

#define LMASK (255 << 4)
#define RMASK (255 >> 4)
#define LGET(d) ((d&LMASK) >> 4)
#define RGET(d) (d&RMASK)
#define LSET(d,n) (d=((d&RMASK) | (n << 4)))
#define RSET(d,n) (d=((d&LMASK) | n))

int main()
{
    unsigned char b=0;
    for(LSET(b,1);LGET(b)<=9;LSET(b,(LGET(b)+1)))
        for(RSET(b,1);RGET(b)<=9;RSET(b,(RGET(b)+1)))
            if(LGET(b)%3!=RGET(b)%3)
                printf("A=%d,B=%d\n",LGET(b),RGET(b));
    return 0;
}

 

还有一种更为简单明了的方法

struct 
{
    unsigned char a:4;
    unsigned char b:4;
}chess;

int main()
{
    for(chess.a=1;chess.a<=9;++chess.a)
        for(chess.b=1;chess.b<=9;++chess.b)
            if(chess.a%3!=chess.b%3)
                printf("A=%d,B=%d\n",chess.a,chess.b);
    return 0;
}