【题目分析】
沉迷水题，吃枣药丸。
【代码】
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
#define F(i,j,k) for (int i=j;i<=k;++i)
#define ll long long
int cot[512],c1[512],c2[512][512],n,p;
ll dp[10][512][90];
void print(int x)
{F(i,0,n-1) printf("%d",(x>>i)&1);
}
void init()
{F(i,0,(1<<n)-1){int x=i,ret=0;while (x) ret+=x&1,x>>=1;cot[i]=ret;}F(i,0,(1<<n)-1)if ((!((i>>1)&i))&&(!((i<<1)&i))) c1[i]=1;F(i,0,(1<<n)-1) if (c1[i])F(j,0,(1<<n)-1) if (c1[j])if ((!((j>>1)&i))&&(!((j<<1)&i))&&(!(j&i))){
// print(i); printf("---> "); print(j); printf("\n");c2[i][j]=1;}
}
int main()
{scanf("%d%d",&n,&p);init();F(i,0,(1<<n)-1) if (c1[i]) dp[1][i][cot[i]]=1;F(i,1,n-1) F(j,0,(1<<n)-1)F(k,0,p) F(l,0,(1<<n)-1)if (c2[j][l]){
// printf("dp[%d] ",i+1); print(l); printf(" %d += dp[%d] ",k+cot[l],i); print(j); printf(" %d = %d\n",k,dp[i][j][k]);dp[i+1][l][k+cot[l]]+=dp[i][j][k];}ll ans=0;F(i,0,(1<<n)-1) ans+=dp[n][i][p];printf("%lld\n",ans);
}
