Submission #236874

#	Time	Username	Problem	Language	Result	Execution time	Memory
236874		anubhavdhar	Tents (JOI18_tents)	C++14	100 / 100	868 ms	71288 KiB

tents

#include<bits/stdc++.h>

#define ll long long int
#define pb push_back
#define mp make_pair
#define FOR(i,n) for(i=0;i<(n);++i)
#define FORe(i,n) for(i=1;i<=(n);++i)
#define FORr(i,a,b) for(i=(a);i<(b);++i)
#define FORrev(i,n) for(i=(n);i>=0;--i)
#define F0R(i,n) for(int i=0;i<(n);++i)
#define F0Re(i,n) for(int i=1;i<=(n);++i)
#define F0Rr(i,a,b) for(ll i=(a);i<(b);++i)
#define F0Rrev(i,n) for(int i=(n);i>=0;--i)
#define ii pair<ll,ll>
#define vi vector<ll>
#define vii vector<ii>
#define ff first 
#define ss second
#define cd complex<double>
#define vcd vector<cd>
#define ldd long double
#define dbgLine cout<<"Line : "<<__LINE__<<'\n'
#define all(x) (x).begin(),(x).end()

using namespace std;

const short int __PRECISION = 10;

const ll MOD = 1e9+7;
const ll INF = 1e17 + 1101;
const ll LOGN = 17;
const ll MAXN = 3001;
const ll ROOTN = 320;

const ldd PI = acos(-1);
const ldd EPS = 1e-7;

ll dp[MAXN][MAXN];

#define C(a) ((((a)*(a-1))/2)%MOD)

ll DP(int i, int j)
{
	if(i < 0 or j < 0)	return 0;
	ll& t = dp[i][j];
	if(t != -1)	return t;
	t = 0;
	t += 5*DP(i - 1, j - 1);
	t += ((i-1)*DP(i-2, j-1))%MOD;
	t += ((j-1)*DP(i-1, j-2))%MOD;
	t += ((j-1)*((4*DP(i-1,j-2)+(i-1)*DP(i-2,j-2))%MOD))%MOD;
	t += ((i-1)*((4*DP(i-2,j-1)+(j-1)*DP(i-2,j-2))%MOD))%MOD;
	t += (DP(i-1,j-3)*C(j-1))%MOD;
	t += (DP(i-3,j-1)*C(i-1))%MOD;
	t += (((C(i-1)*(j-1))%MOD)*((4*DP(i-3,j-2)+(i-3)*DP(i-4,j-2))%MOD))%MOD;
	t += (((C(j-1)*(i-1))%MOD)*((4*DP(i-2,j-3)+(j-3)*DP(i-2,j-4))%MOD))%MOD;
	t += (((C(i-1)*C(j-1))%MOD)*DP(i-3,j-3))%MOD;
	t += (((16*DP(i-2,j-2) + 4*(j-2)*DP(i-2,j-3) + 4*(i-2)*DP(i-3,j-2) + (i-2)*(j-2)*DP(i-3, j-3))%MOD) * ((i-1)*(j-1)))%MOD;
	t %= MOD;
	assert(t == dp[i][j]);
	return t;
}

int main()
{
	/*
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	*/
	int i, j;
	FOR(i, MAXN)
		FOR(j, MAXN)
			dp[i][j] = (i == 0 || j == 0) ? 1 : -1;
	cin>>i>>j;
	cout<<(DP(i, j) + MOD - 1) % MOD << endl;
	return 0;
}

• Subtask 1: 48 / 48
• Subtask 2: 52 / 52