제출 #913820

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
913820		Mirali7	캥거루 (CEOI16_kangaroo)	C++17	100 / 100	31 ms	620 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;
	vector<ll> dp(n + 1); dp[0] = 1;
	forn(i, n) {
		vector<ll> ndp(n + 1);
		dforn(j, 0, n) {
			if (i == s) {
				if (j) (ndp[j] += dp[j]) %= mod;
				if (j < n) (ndp[j + 1] += dp[j]) %= mod;
			}
			else if (i == f) {
				if (j) (ndp[j] += dp[j]) %= mod;
				if (j < n) (ndp[j + 1] += dp[j]) %= mod;
			}
			else {
				if (j > 1) (ndp[j - 1] += dp[j] * (j - 1) % mod) %= mod;
				if (j < n) (ndp[j + 1] += dp[j] * max(0, j + 1 - (i > s) - (i > f)) % mod) %= mod;
			}
		}
		dp = ndp;
	}
	cout << dp[1] << '\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: 6 / 6
• Subtask 2: 30 / 30
• Subtask 3: 15 / 15
• Subtask 4: 49 / 49