This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
//https://www.instagram.com/_modwwe/
#pragma GCC optimize("Ofast,unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2")
#include<bits/stdc++.h>
#define int long long
//#define ll long long
#define down cout<<'\n';
#define debug cout<<" cucuucucuuu",down
#define NHP ios_base::sync_with_stdio(0);cout.tie(0);cin.tie(0);
#define modwwe int t;cin>>t; while(t--)
#define bit(i,j) (i>>j&1)
#define sobit(a) __builtin_popcountll(a)
#define task "test"
#define fin(x) freopen(x".inp","r",stdin)
#define fou(x) freopen(x".ans ","w",stdout)
#define pb push_back
#define checktime cerr << (double)clock() / CLOCKS_PER_SEC * 1000 << " ms";
using namespace std;
void phongbeo();
const int inf=1e18;
const int mod2=1e9+7;
const int mod1=998244353;
struct icd
{
int a,b;
};
struct ib
{
int a;
int b;
};
struct ic
{
int a,b,c;
};
struct id
{
int a,b,c,d;
};
struct ie
{
int a,b,c, d,e,f;
};
int n,m,s1,s2,s4,s3,sf,k,r,mid,s5,s6,mx,s7,s8,s9,mx2,res,dem2=0,dem=0,l;
int i,s10,s12;
int el=29;
main()
{
#ifndef ONLINE_JUDGE
/// fin(task),fou(task);
#endif
NHP
/// cin>>s1;
// modwwe
phongbeo();
}
int fac[3001];
int invf[3001];
int dp[3001][3001];
int ipow(int x, int p){
int ret = 1, piv = x;
while(p){
if(p&1) ret *= piv;
piv *= piv;
ret %= mod2;
piv %= mod2;
p >>= 1;
}
return ret;
}
int bino(int x, int y){
return fac[x] * (invf[x-y] * invf[y] % mod2) % mod2;
}
void phongbeo()
{
cin>>n>>m;
fac[0]=invf[0]=1;
for(int i=1;i<=n;i++){
fac[i]=(i*fac[i-1])%mod2;
invf[i] = ipow(fac[i], mod2 - 2);
}
dp[0][m]=1;
for(int i=1;i<=n;i++)
for(int j=0;j<m;j++)
{
dp[i][j]=(dp[i-1][j+1]*4*(j+1)+dp[i][j])%mod2;
dp[i][j]=(dp[i-1][j+2]*(j+2)*(j+1)/2+dp[i][j])%mod2;
dp[i][j]=(dp[i-2][j+1]*(j+1)*(i-1)+dp[i][j])%mod2;
}
s3=0;
for(int i=1;i<=n;i++){
s2=bino(n,i);
for(int j=0;j<m;j++)
s3+=dp[i][j]*s2;
}
cout<<s3%mod2;
}
Compilation message (stderr)
tents.cpp:48:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
48 | main()
| ^~~~
tents.cpp: In function 'void phongbeo()':
tents.cpp:84:2: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
84 | for(int i=1;i<=n;i++)
| ^~~
tents.cpp:91:6: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
91 | s3=0;
| ^~
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