Author: David Dahlem
Date: 09:09:48 02/11/06
Go up one level in this thread
On February 10, 2006 at 07:04:19, h.g.muller wrote:
>This one seems to do it. It took me 70 miniutes, (without cheating or debugger),
>so the other 3 problems better be really easy compared to this one...
>
>int vectors[] = {16,15,17,0,-16,-15,-17,0,1,-1,16,-16,0,
> 1,-1,16,-16,15,-15,17,-17,0,
> 14,-14,18,-18,31,-31,33,-33,0};
>int firstdir[] = {2,-1,3,21,12,16,7,12};
>
>char board[128];
>int orig, targ;
>
>int negamax(int color, int depth)
>{
> int origsqr, targsqr, bestorig, besttarg, score, bestscore,
> piece, piecetype, victim, dirnr, stepvec;
>
> bestscore = depth<=1 ? 0 : -2;
>
> for(origsqr=0; origsqr<128; origsqr = (origsqr+9) & ~8)
> {
> piece = board[origsqr];
> piecetype = piece&7;
> if(piece&color)
> {
> dirnr = firstdir[piecetype];
> while(stepvec = vectors[++dirnr])
> {
> targsqr = origsqr;
> do {
> targsqr += stepvec;
> if(targsqr & 0x88) break;
> victim = board[targsqr];
> if(victim & color) break;
> if(piecetype<3 &&
> ( (victim==0) != ((stepvec&7)==0) )
> ) break;
>
> if((victim&7) == 4) {bestscore = 2; goto cutoff;}
>
> if(depth>1)
> {
> board[origsqr] = 0; board[targsqr] = piece;
> score = -negamax(24-color, depth-1);
> board[origsqr] = piece; board[targsqr] = victim;
> /*printf("%d: (%2x,%2x) %d %d\n", depth, origsqr,
>targsqr, score, bestscore);/**/
>
> if(score>bestscore)
> {
> bestscore = score;
> bestorig = origsqr;
> besttarg = targsqr;
> }
> }
> victim += (piecetype < 5);
> } while(victim==0);
> }
> }
> }
> if(bestscore == -1)
> bestscore = -negamax(24-color, 0)/2;
>cutoff:
> orig = bestorig;
> targ = besttarg;
> return bestscore;
>}
>
>int main(void)
>{
> int i, j, k, s;
> char buf[80], c;
>
> for(i=0;i<128;i+=16)
> {
> for(j=0;j<8;j++)
> { c = getchar();
> k=8;
> if(c>='a') {c += 'A'-'a'; k=16;}
> switch(c)
> {
> case 'K': s=4; break;
> case 'Q': s=7; break;
> case 'R': s=6; break;
> case 'B': s=5; break;
> case 'N': s=3; break;
> case 'P': s=k==8?1:2; break;
> case '.': s=0; break;
> default: printf("bad piece %c at %d,%d\n",c,i,j); exit(0);
> }
> if(s) s+= k;
> board[i+j] = s;
> }
> if(getchar() != '\n') {printf("bad format\n"); exit(0);}
> }
>
> for(i=2;i<=4;i+=2)
> if(negamax(8,i+1))
> {
> printf("mate in %d by %c%c%c%c\n", i/2,
> (orig&7)+'a', (orig>>4)+'1',
> (targ&7)+'a', (targ>>4)+'1');
> exit(0);
> }
> printf("no mate found\n");
>}
How do you enter mate-in-1 positions to this program?
Regards
Dave
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