状态压缩动规

#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<cmath>
#include<queue>
#include<stack>
#include<algorithm>
#define int long long
using namespace std;
const int N=(1<<11);
const int INF=0x3f3f3f3f;
int dp[12][N][100],check[N];
int n,m;
void init(){
	for(int i=0;i<(1<<n);i++){
		int x=i;
		while(x>0){
			check[i]++;
			x-=x&(-x);
		}
	}
}
signed main(){
	cin >> n >> m;
	init();
	for(int i=0;i<(1<<n);i++){
		dp[1][i][check[i]]=1;
	}
	for(int le=2;le<=n;le++){
		for(int i=0;i<(1<<n);i++){
			if(i&(i<<1))continue;
			for(int j=0;j<(1<<n);j++){
				if((j&(j<<1))||(i&j)||(i&(j<<1))||(i&(j>>1)))continue;
				for(int k=check[i];k<=m;k++){
					dp[le][i][k]+=dp[le-1][j][k-check[i]];
				}
			}
		}
	}
	int ans=0;
	for(int i=0;i<(1<<n);i++){
		ans+=dp[n][i][m];
	}
	cout << ans;
	return 0;
}