Submission #936868

#	Time	Username	Problem	Language	Result	Execution time	Memory
936868		horiseun	Tents (JOI18_tents)	C++17	100 / 100	84 ms	70760 KiB

tents

#include <iostream>
#include <vector>
#include <tuple>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <deque>
#include <cmath>
#include <array>
#include <random>
#include <climits>
#include <cassert>
#include <algorithm>
using namespace std;

template<typename A, typename B> ostream& operator << (ostream &os, const pair<A, B> &p) { return os << '(' << p.first << ", " << p.second << ')'; }
template<typename T_container, typename T = typename enable_if<!is_same<T_container, string>::value, typename T_container::value_type>::type> ostream& operator << (ostream &os, const T_container &v) { os << '{'; string sep; for (const T &x : v) { os << sep << x, sep = ", "; } return os << '}'; }
void D_out() { cerr << endl; }
template<typename Head, typename... Tail> void D_out(Head H, Tail... T) { cerr << ' ' << H; D_out(T...); }

#ifdef DEBUG
	#define D(...) cerr << '(' << #__VA_ARGS__ << "):", D_out(__VA_ARGS__)
#else
	#define D(...)
#endif

#define int long long
#define ll long long
#define ld long double
#define f first
#define s second
#define sz(x) ((int) x.size())
#define all(x) (x).begin(), (x).end()

const ll MOD = 1e9 + 7;
const ll INF = 1e18;

int r, c, dp[3005][3005], ans;

void solve() {
	cin >> r >> c;
	dp[r][c] = 1;
	for (int i = r; i; i--) {
		for (int j = c; j >= 0; j--) {
			(dp[i - 1][j] += dp[i][j]) %= MOD;
			if (j > 0) {
				(dp[i - 1][j - 1] += j * dp[i][j] * 4) %= MOD;
				if (i > 1) {
					(dp[i - 2][j - 1] += j * (i - 1) * dp[i][j]) %= MOD;
				}
			}
			if (j > 1) (dp[i - 1][j - 2] += j * (j - 1) / 2 * dp[i][j]) %= MOD;
		}
	}
	for (int j = c - 1; j >= 0; j--) {
		(ans += dp[0][j]) %= MOD;
	}
	cout << ans << "\n";
}

signed main() {
	ios_base::sync_with_stdio(false);
	cin.tie(0);	

	int t = 1; //cin >> t;
	for (int tc = 1; tc <= t; tc++) {
		//cout << "Case #" << tc << ": ";
		solve();
	}
}

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