bzoj 1087

 1 #include<bits/stdc++.h>
 2 #define inc(i,l,r) for(int i=l;i<=r;i++)
 3 #define dec(i,l,r) for(int i=l;i>=r;i--)
 4 #define link(x) for(edge *j=h[x];j;j=j->next)
 5 #define mem(a) memset(a,0,sizeof(a))
 6 #define inf 1e9
 7 #define ll long long
 8 #define succ(x) (1<<x)
 9 #define NM 10
10 using namespace std;
11 int read(){
12     int x=0,f=1;char ch=getchar();
13     while(!isdigit(ch)){if(ch==‘-‘)f=-1;ch=getchar();}
14     while(isdigit(ch))x=x*10+ch-‘0‘,ch=getchar();
15     return x*f;
16 }
17 ll d[NM][succ(NM)][NM*NM],ans;
18 int k,n,m,c[succ(NM)],b[succ(NM)];
19 int main(){
20     n=read();k=read();
21     inc(i,0,succ(n)-1)
22     if(!(i&(i<<1)))b[++m]=i,c[m]=__builtin_popcount(i),d[1][m][c[m]]=1;
23     inc(i,2,n)
24     inc(t,1,m)
25     inc(v,0,k)
26     if(c[t]<=v){
27         int _t=0;
28         inc(j,0,n-1)
29         if((b[t]&succ(j-1))||(b[t]&succ(j))||(b[t]&succ(j+1)))_t+=succ(j);
30         inc(j,1,m)
31         if(!(b[j]&_t)&&c[t]<=v)
32         d[i][t][v]+=d[i-1][j][v-c[t]];
33     }
34 //    inc(i,1,n){inc(t,1,m){
35 //    inc(j,0,k)printf("%d ",d[i][t][j]);
36 //    printf("\n");}
37 //    printf("\n");}
38     inc(t,1,m)ans+=d[n][t][k];
39     printf("%lld\n",ans);
40     return 0;
41 }