ural 1519 Formula 1

#include<queue>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int bi=1e8;
int i;
struct na{
    int x,z;
    na(int xx,int zz):x(xx),z(zz){}
};
struct big{
    int a[4];
    big(){
        memset(a,0,sizeof(a));
        a[0]=1;
    }
    big operator =(int x){
        if (x==0){
            memset(a,0,sizeof(a));
            a[0]=1;
            return *this;
        }
        a[0]=0;
        while (x){
            a[0]++;
            a[a[0]]=x%bi;
            x/=bi;
        }
        if (!a[0]) a[0]=1;
        return *this;
    }
    big operator +(const big &x){
        big r;
        if (a[0]<x.a[0]) r.a[0]=x.a[0];else r.a[0]=a[0];
        for (i=1;i<=r.a[0];i++) r.a[i]=a[i]+x.a[i];
        for (i=1;i<=r.a[0];i++)
        if (r.a[i]>=bi){
            r.a[i]-=bi;r.a[i+1]++;
            if (i==r.a[0]) r.a[0]++;
        }
        return r;
    }
}ans;
int n,m,x,y,z,a[21],k,p1,p2,end;
bool map[21][21];
big f[2][1594324];
int v[2][1594324];
queue <na> q;
inline int gx(int x,int q1,int q2){k=0;for (register int i=m+1;i;i--) k=k*3+(i==x?q1:(i==x+1?q2:a[i]));return k;}
inline void up(int x,int z,big lj){
    x++;
    k=x%2;
    if (v[k][z]!=x) v[k][z]=x,f[k][z]=0,q.push(na(x,z));
    f[k][z]=f[k][z]+lj;
}
char c[10];
int main(){
    register int i,j;
    scanf("%d%d",&n,&m);
    for (j=1;j<=n;j++){
        scanf("%s",c);
        for (i=1;i<=m;i++)
        map[i][j]=c[i-1]==‘.‘;
    }
    end=n*m-1;
    while(!map[end%m+1][end/m+1]) end--;
    f[0][0]=v[0][0]=1;
    q.push(na(0,0));
    while(!q.empty()){
        na no=q.front();q.pop();
        big an=f[no.x%2][no.z];
        if(no.x%m==0) no.z*=3;
        x=no.x%m+1;y=no.x/m+1;
        for (i=1;i<=m+1;i++) a[i]=0;
        for (i=1,j=no.z;j;i++,j/=3) a[i]=j%3;
        if (!map[x][y])up(no.x,gx(x,0,0),an);else
        if (a[x]==1&&a[x+1]==2){
            if (no.x==end)  ans=ans+an;
        }else if (a[x]==2&&a[x+1]==1) up(no.x,gx(x,0,0),an);else
        if (a[x]==0&&a[x+1]==0){
            if (map[x][y+1]&&map[x+1][y]) up(no.x,gx(x,1,2),an);
        }else if (a[x]==0){
            if (map[x+1][y]) up(no.x,gx(x,0,a[x+1]),an);
            if (map[x][y+1]) up(no.x,gx(x,a[x+1],0),an);
        }else if (a[x+1]==0){
            if (map[x+1][y]) up(no.x,gx(x,0,a[x]),an);
            if (map[x][y+1]) up(no.x,gx(x,a[x],0),an);
        }else if (a[x]==a[x+1]){
            p1=p2=0;
            if (a[x]==1)
            for (j=0,i=x+2;i<=m;i++){
                if (a[i]==1) j--;
                if (a[i]==2) j++;
                if (j>0&&!p1) p1=i,j--;
                if (j>0&&p1){p2=i;break;}
            }else
            for (j=0,i=x-1;i;i--){
                if (a[i]==1) j++;
                if (a[i]==2) j--;
                if (j>0&&!p2) p2=i,j--;
                if (j>0&&p2){p1=i;break;}
            }
            a[p1]=1;a[p2]=2;up(no.x,gx(x,0,0),an);
        }
    }
    printf("%d",ans.a[ans.a[0]]);
    for (i=ans.a[0]-1;i;i--) printf("%08d",ans.a[i]);
}