pku1077 Eight

 

A*

Memory:6384K   Time:79MS

太烂了,估计是hash太肿...有空再来优化

#include  < iostream >
#include  < string >
#include  < vector >
#include  < queue >
using   namespace  std;

#define  MAXN 362881

int  fac[ 9 ] = { 40320 , 5040 , 720 , 120 , 24 , 6 , 2 , 1 , 1 };
int  stseq[ 9 ],edseq[ 9 ] = { 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 0 },stkey,edkey;

int  g[MAXN],f[MAXN],mk[MAXN],pre[MAXN];
char  op[MAXN];

int  h( int  seq[ 9 ]){
     int  i,ret = 0 ;
     for (i = 0 ;i < 9 ;i ++ )
        ret += abs(seq[i] - edseq[i]);
     return  ret;
     // return 0;
}


int  getkey( int  seq[ 9 ]){
     int  nsn,sum = 0 ;
     for ( int  i = 0 ;i < 9 ;i ++ ){
        nsn = 0 ;
         for ( int  j = i + 1 ;j < 9 ;j ++ )
             if (seq[i] > seq[j])
                nsn ++ ;
        sum += nsn * fac[i];
        
    }
     return  sum;
}

void  getseq( int  key, int *   & seq, int   & pos){ // key of "876543210" = 40319 < 40320
     int  i,j,k;
     for (i = 0 ;i < 9 ;i ++ ){
        seq[i] = key / fac[i];
        key %= fac[i];
    }

     bool  used[ 9 ] = { 0 };
    used[seq[ 0 ]] = true ;
     if (seq[ 0 ] == 0 )
            pos = 0 ;
     for (i = 1 ;i < 9 ;i ++ ){
        j = 0 ;
         for (k = 0 ;j < seq[i]  &&  k < 9 ;k ++ )
             if ( ! used[k])
                j ++ ;
         while (used[k])
            k ++ ;
        seq[i] = k;
        used[k] = true ;
         if (seq[i] == 0 )
            pos = i;
    }

}


class  CP{
public :
     int   operator ()( int  t1, int  t2){
         return  f[t1] > f[t2];
    }
};

void  output( int  key){
     int   * seq,i;
     string  ans = "" ;
    seq = new   int [ 9 ];
     for (i = g[key] - 1 ;i >= 0 ;i -- ){
        ans += op[key];
        key = pre[key];
    }
     for (i = ans.length() - 1 ;i >= 0 ;i -- )
        cout << ans[i];
    cout << endl;
}

int  astar(){
     int  curkey, * curseq,pos,nkey;
    curseq = new   int [ 9 ];

    memset(mk, 0 , sizeof (mk));
    priority_queue <   int , vector < int >  ,CP >  qu;

    stkey = getkey(stseq);
    mk[stkey] = 1 ;
    g[stkey] = 0 ;
    f[stkey] = g[stkey] + h(stseq);
    qu.push(stkey);

    f[ 362880 ] =- 1 ;

    edkey = getkey(edseq);

     while ( ! qu.empty()){
        curkey = qu.top();
        qu.pop();
        mk[curkey] = 2 ;

         if (curkey == edkey){
            output(curkey);
             return  g[curkey];
        }

        getseq(curkey,curseq,pos);

         if (pos >= 3 ){
            swap(curseq[pos],curseq[pos - 3 ]);
            nkey = getkey(curseq);
             if (mk[nkey] == 0 ){
                mk[nkey] = 1 ;
                pre[nkey] = curkey;
                op[nkey] = ' u ' ;
                g[nkey] = g[curkey] + 1 ;
                f[nkey] = g[nkey] + h(curseq);
                qu.push(nkey);
            }
             else   if (mk[nkey] == 1 ){
                 if (g[curkey] + 1 < g[nkey]){
                    pre[nkey] = curkey;
                    op[nkey] = ' u ' ;
                    g[nkey] = g[curkey] + 1 ;
                    f[nkey] = g[nkey] + h(curseq);
                    qu.push( 362880 );
                    qu.pop();
                }
            }
            swap(curseq[pos],curseq[pos - 3 ]);
        }

         if (pos < 6 ){
            swap(curseq[pos],curseq[pos + 3 ]);
            nkey = getkey(curseq);
             if (mk[nkey] == 0 ){
                mk[nkey] = 1 ;
                pre[nkey] = curkey;
                op[nkey] = ' d ' ;
                g[nkey] = g[curkey] + 1 ;
                f[nkey] = g[nkey] + h(curseq);
                qu.push(nkey);
            }
             else   if (mk[nkey] == 1 ){
                 if (g[curkey] + 1 < g[nkey]){
                    pre[nkey] = curkey;
                    op[nkey] = ' d ' ;
                    g[nkey] = g[curkey] + 1 ;
                    f[nkey] = g[nkey] + h(curseq);
                    qu.push( 362880 );
                    qu.pop();
                }
            }
            swap(curseq[pos],curseq[pos + 3 ]);
        }

         if (pos % 3 != 2 ){
            swap(curseq[pos],curseq[pos + 1 ]);
            nkey = getkey(curseq);
             if (mk[nkey] == 0 ){
                mk[nkey] = 1 ;
                pre[nkey] = curkey;
                op[nkey] = ' r ' ;
                g[nkey] = g[curkey] + 1 ;
                f[nkey] = g[nkey] + h(curseq);
                qu.push(nkey);
            }
             else   if (mk[nkey] == 1 ){
                 if (g[curkey] + 1 < g[nkey]){
                    pre[nkey] = curkey;
                    op[nkey] = ' r ' ;
                    g[nkey] = g[curkey] + 1 ;
                    f[nkey] = g[nkey] + h(curseq);
                    qu.push( 362880 );
                    qu.pop();
                }
            }
            swap(curseq[pos],curseq[pos + 1 ]);
        }

         if (pos % 3 != 0 ){
            swap(curseq[pos],curseq[pos - 1 ]);
            nkey = getkey(curseq);
             if (mk[nkey] == 0 ){
                mk[nkey] = 1 ;
                pre[nkey] = curkey;
                op[nkey] = ' l ' ;
                g[nkey] = g[curkey] + 1 ;
                f[nkey] = g[nkey] + h(curseq);
                qu.push(nkey);
            }
             else   if (mk[nkey] == 1 ){
                 if (g[curkey] + 1 < g[nkey]){
                    pre[nkey] = curkey;
                    op[nkey] = ' l ' ;
                    g[nkey] = g[curkey] + 1 ;
                    f[nkey] = g[nkey] + h(curseq);
                    qu.push( 362880 );
                    qu.pop();
                }
            }
            swap(curseq[pos],curseq[pos - 1 ]);
        }
    }

     return   - 1 ;
}


int  main(){
     int  i;
     char  ch;

     for (i = 0 ;i < 9 ;i ++ ){
        cin >> ch;
         if (ch == ' x ' )
            stseq[i] = 0 ;
         else
            stseq[i] = ch - ' 0 ' ;
    }

     if (astar() ==- 1 )
        cout << " unsolvable\n " ;

     return   0 ;
}