제출 #913801

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
913801		Mirali7	캥거루 (CEOI16_kangaroo)	C++17	0 / 100	1 ms	348 KiB

kangaroo

//#include <udacha>
#include <iostream>
#include <string>
#include <deque>
#include <vector>
#include <algorithm>
#include <iomanip>
#include <map>
#include <set>
#include <queue>
#include <fstream>
#include <stack>
#include <cmath>
#include <bitset>
#include <unordered_set>
#include <unordered_map>
#include <random>
#include <array>
#include <chrono>
#include <functional>
#include <numeric>
#include <complex>

using namespace std;

#define ll long long
#define ld long double
#define ull uint64_t
#define pll pair<ll, ll>
#define pii pair<int, int>
#define pli pair<ll, int>
#define plli pair<pll, int>
#define pld pair<ld, ld>
#define fst first
#define snd second
#define pdi pair<ld, int>
#define pdd pair<double, double>
#define piii pair<int, pii>

#define forn(i, n) for (int i = 1; i <= n; i++)
#define dforn(i, a, b) for (int i = a; i <= b; i++) 
#define rforn(i, n) for (int i = n; i >= 1; i--)
#define rdforn(i, a, b) for (int i = b; i >= a; i--)
#define sforn(i, a, b, s) for (ll i = a; i <= b; i += s)
#define aforn(v, a) for (auto& v : a)
#define sz(a) ((int)a.size())

const int mod = 1e9 + 7;
const ld pi = acos(-1);
const ll N = 2e5 + 1;
const ll inf = 3e18;
const int iinf = 1e9;
const ld dinf = 1e16;
const double eps = 1e-9;

void solve() {
	int n, s, f;
	cin >> n >> s >> f;
	ll ans = 0;
	dforn(t1, 0, 1) dforn(t2, 0, 1) {
		vector<ll> dp(n + 3);
		dp[t1 + t2] = 1;
		int cnt = 0;
		forn(i, n) {
			if (i != s && i != f) cnt++;
			vector<ll> ndp(n + 3);
			dforn(j, 0, n + 2) {
				if (i == s) {
					if (t1 == 1 && j > 0) (ndp[j - 1] += dp[j]) %= mod;
					else if (t1 == 0 && j < n + 2) (ndp[j + 1] += dp[j]) %= mod;
				}
				else if (i == f) {
					if (t2 == 1 && j > 0) (ndp[j - 1] += dp[j]) %= mod;
					else if (t2 == 0 && j < n + 2) (ndp[j + 1] += dp[j]) %= mod;
				}
				else {
					if (j < n + 2) (ndp[j + 1] += dp[j] * max(0, j + 1 - t1 - t2) % mod) %= mod;
					if (j) (ndp[j - 1] += dp[j] * max(0, j - 1 - t1 - t2 + (cnt == n - 2)) % mod) %= mod;
				}
			}
			dp = ndp;
		}
		(ans += dp[1]) %= mod;
	}
	cout << ans << '\n';
}

int main()
{
	ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
	int t = 1;
	//cin >> t;
	while (t--) solve();
	return 0;
}

• Subtask 1: 0 / 6
• Subtask 2: 0 / 30
• Subtask 3: 0 / 15
• Subtask 4: 0 / 49