Submission #519501

#	Time	Username	Problem	Language	Result	Execution time	Memory
519501		Samboor	Kangaroo (CEOI16_kangaroo)	C++17	100 / 100	32 ms	31820 KiB

kangaroo

// Grzegorz Ryn
// V LO Kraków

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<bool> vb;
typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef vector<ll> vl;
typedef vector<vector<ll>> vvl;

#define pb push_back
#define eb emplace_back
#define mp make_pair
#define mt make_tuple
#define st first
#define nd second
#define FOR(__VAR, __START, __END) for(int __VAR=__START; __VAR<=__END; __VAR++)
#define FORB(__VAR, __START, __END) for(int __VAR=__START; __VAR>=__END; __VAR--)
#define FORK(__VAR, __START, __END, __DIFF) for(int __VAR=__START; __VAR<=END; __VAR+=__DIFF)
#define all(__VAR) (__VAR).begin(), (__VAR).end()
#define rall(__VAR) (__VAR).rbegin(), (__VAR).rend()
#define DEBUG(__VAR) cout << #__VAR << ": " << __VAR << endl;

template<typename __T1, typename __T2>
ostream & operator<<(ostream &out, pair<__T1, __T2> &__VAR) {
	cout << "[" << __VAR.st << ", " << __VAR.nd << "]";
	return out;
}

template<typename __T>
ostream & operator<<(ostream &out, vector<__T> &__VAR) {
	cout << "[";
	FOR(i, 0, (int)__VAR.size()-2)
		cout << __VAR[i] << ", ";
	if(__VAR.size()>0)
		cout << __VAR[__VAR.size()-1];
	cout << "]" << endl;
	
	return out;
}

const ll INF = 1e17, MOD = 1'000'000'000 + 7;

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	
	int N, b, e;
	cin >> N >> b >> e;
	
	vector<vector<ll>> dp(N+1, vector<ll>(N+1));
	dp[1][1] = 1;
	for(ll i=2; i<=N; i++) {
		for(ll j=1; j<=N; j++) {
			if(i == b || i == e) {
				dp[i][j] = (dp[i-1][j-1] + dp[i-1][j]) % MOD;
				continue;
			}
			dp[i][j] = (j*dp[i-1][j+1]) % MOD;
			ll pos = j;
			if(b < i) {
				pos--;
			}
			if(e < i) {
				pos--;
			}
			dp[i][j] += dp[i-1][j-1] * pos;
			dp[i][j] %= MOD;
		}
	}
	
	cout << dp[N][1] << '\n';

	return 0;
}

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