简单算法—幻方构造

/幻方构造(l!=2)

#define MAXN 100

void dllb(int l,int si,int sj,int sn,int d[][MAXN]){

       int n,i=0,j=l/2;

       for (n=1;n<=l*l;n++){

              d[i+si][j+sj]=n+sn;

              if (n%l){

                     i=(i)?(i-1):(l-1);

                     j=(j==l-1)?0:(j+1);

        }

              else

                     i=(i==l-1)?0:(i+1);

    }

}

void magic_odd(int l,int d[][MAXN]){

       dllb(l,0,0,0,d);

}

void magic_4k(int l,int d[][MAXN]){

       int i,j;

       for (i=0;i<l;i++)

              for (j=0;j<l;j++)

                     d[i][j]=((i%4==0||i%4==3)&&(j%4==0||j%4==3)||(i%4==1||i%4==2)&&(j%4==1||j%4==2))?(l*l-(i*l+j)):(i*l+j+1);

}

void magic_other(int l,int d[][MAXN]){

       int i,j,t;

       dllb(l/2,0,0,0,d);

       dllb(l/2,l/2,l/2,l*l/4,d);

       dllb(l/2,0,l/2,l*l/2,d);

       dllb(l/2,l/2,0,l*l/4*3,d);

       for (i=0;i<l/2;i++)

              for (j=0;j<l/4;j++)

                     if (i!=l/4||j)

                            t=d[i][j],d[i][j]=d[i+l/2][j],d[i+l/2][j]=t;

       t=d[l/4][l/4],d[l/4][l/4]=d[l/4+l/2][l/4],d[l/4+l/2][l/4]=t;

       for (i=0;i<l/2;i++)

              for (j=l-l/4+1;j<l;j++)

                     t=d[i][j],d[i][j]=d[i+l/2][j],d[i+l/2][j]=t;

}

void generate(int l,int d[][MAXN]){

       if (l%2)

              magic_odd(l,d);

       else if (l%4==0)

              magic_4k(l,d);

       else

              magic_other(l,d);

}