问计算路径总数

EN

S=7
D=-1j

R=[0,4,7,1+1j,3+1j,1+3j,4+3j,7j,3+7j,7+7j,8j,3+8j]
Z={}
for i in range(4096):
 d=D;p=R[S];L=[]
 while len(L)<12:
  p+=d;P=[(abs(r-p),r)for r in R if r-p==abs(r-p)*d]
  if not P:break
  p=min(P)[1];d*=1j**(i>>R.index(p)&1);L+=[p]
  if p==R[S]:Z[tuple(L)]=1;break
print len(Z)

program c1

   mov bp,1000h
   mov di,bp
   mov cx,bp
   xor ax,ax
   rep stosw
   mov bl,b[82h]
   sub bl,'a'-1
   mov bh,ch
   add bx,bx
   mov cl,b[83h]
   sub cl,48
   shl cl,2
   mov di,bx
   call l2
   mov dx,bp
   add b[bp],48
   mov b[bp+1],'
   mov ah,9
   int 21h
   ret
l1:inc b[bp]
   cmp di,bx
   je ret
   dec b[bp]
   cmp b[di+bp],0
   jne ret
   call l2
   sub cl,4
l2:mov dx,[di+l3-2]
   ror dx,cl
   and dx,15
   jz ret
   mov b[di+bp],1
   pusha
   mov di,dx
   add di,di
   call l1
   popa
   mov b[di+bp],0
   ret
l3:xor al,b[bx+si]
   inc ax
   add w[si+09510],sp
   and ax,ax
   add al,087
   add b[bx+si+0906],dh
   pusha
   add b[bx+si+0b],cl
   xor b[si],cl
   jpe l4
l4:pop bx

D=3;//starting direction
C=21;//starting rock

function a(a){return a+="",(a[0]-1)*5+(a[1]-1)}
function b(a){var b=!1,c=C+"";a==4?(h=c[0]+(c[1]-1))[1]>0&&(b=!0):a==3?(h=-(-c[0]-1)+c[1]+"")[0]<6&&(b=!0):a==2?(h=c[0]+ -(-c[1]-1))[1]<6&&(b=!0):(h=c[0]-1+c[1])[0]>0&&(b=!0);if(b)return C=h*1,!0}
function c(){var c=C;while(b(D)&&F[a(C)]==0);if(C!=c&&F[a(C)]==1)return!0}
function d(){if(c()){F[C]++;var a=D,b=C;C!=B?(d(),C=b,D=a,D==1?D=4:D--,d()):(A++,F=E)}}
A=0,B=C,E=F="1010010101010100110010011".split(""),d(),alert(A)

dir=3;
start=21;

//transforms row-column notation to array index
function toAV(a){
    return a+="",(a[0]-1)*5+(a[1]-1);
}

//advance one square on the current direction
//returns true when it succeed
function walk(num){
    var walkbol=false,str=xy+"";
    if(num==4){
        if((wal_rec=str[0]+(str[1]-1))[1]>0){
            walkbol=true;
        }
    }else if(num==3){
        if((wal_rec=-(-str[0]-1)+str[1]+"")[0]<6){
            walkbol=true;
        }
    }else if(num==2){
        if((wal_rec=str[0]+-(-str[1]-1))[1]<6){
            walkbol=true;
        }
    }else{
        if((wal_rec=(str[0]-1)+str[1])[0]>0){
            walkbol=true;
        }
    }
    if(walkbol){
        xy=wal_rec*1;
        return true;
    }
}

//start walking on the current dir until a)didn't succeed walking or b)step on a rock
//returns true when it moved at least once and it ended above a rock
function nextRock(){
    var str1=xy;
    while(walk(dir)&&map[toAV(xy)]==0){}

    if(xy!=str1&&map[toAV(xy)]==1){
        return true;
    }
}

//if it finds a rock, it calls itself twice
//one with the current direction and one with the direction to its left
function splitways(){
    if(nextRock()){
        map[xy]++;
        var cc=dir,dd=xy;
        if(xy!=start){
            splitways();
            //--
            xy=dd;
            dir=cc;
            dir==1?dir=4:dir--;
            splitways();
        }else{
            count++;
            map=xmap;
        }
    }
}

//globals
count=0,xy=start,xmap=map="1010010101010100110010011".split("");

//start
splitways();
alert(count);