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;
}