Submission #1293587

#	Time	Username	Problem	Language	Result	Execution time	Memory
1293587		KickingKun	Asceticism (JOI18_asceticism)	C++20	49 / 100	20 ms	50448 KiB

asceticism

#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define ull unsigned long long
#define ld long double
#define bigint __int128
#define emb emplace_back
#define pb push_back
#define pii pair <int, int>
#define fi first
#define se second
#define all(v) v.begin(), v.end()
#define Task ""

#define MASK(k) (1ull << k)
#define bitcnt(k) __builtin_popcount(k)
#define testBit(n, k) ((n >> k) & 1)
#define flipBit(n, k) (n ^ (1ll << k))
#define offBit(n, k) (n & ~MASK(k))
#define onBit(n, k) (n | (1ll << k))

template <class T> bool minimize(T &a, T b) {if (a > b) {a = b; return true;} return false;}
template <class T> bool maximize(T &a, T b) {if (a < b) {a = b; return true;} return false;}

const int N = 1e5 + 5, lim = 60, mod = 1e9 + 7;
const ll INF = 1e18;

int n, k;

void add(int &a, int b) {
	if ((a += b) >= mod) a -= mod;
}

void sub(int &a, int b) {
	if ((a -= b) < 0) a += mod;
}

int diff(int a, int b) {
	sub(a, b); return a;
}

namespace sub1 {
	int f[12];
	void solve() {
		vector <int> p(n); iota(all(p), 0);
		// p <-> pos
		int ans = 0;
		do {
			int cnt = 1;
			for (int i = 0; i < n - 1; i++)
				cnt += p[i] > p[i + 1];
			ans += cnt == k;
		} while (next_permutation(all(p)));
		cout << ans;
	}
}

namespace sub2 {
	const int N = 3e2 + 5;
	int dp[N][N][N];

	void solve() {
		dp[1][1][1] = 1;
		for (int i = 2; i <= n; i++) {
			for (int j = 1; j <= min(i, k); j++) {
				for (int pos = 1; pos <= i; pos++) {
					add(dp[i][j][pos], dp[i - 1][j][pos - 1]);
					add(dp[i][j][pos], diff(dp[i - 1][j - 1][i - 1], dp[i - 1][j - 1][pos - 1]));
					add(dp[i][j][pos], dp[i][j][pos - 1]);
				}
			}
		}
		cout << dp[n][k][n];
	}
}

namespace sub3 {
	const int N = 3e3 + 5;
	int dp[N][N];

	void solve() { 
		// dem so luong hoan vi co k-1 cap p[i] > p[i+1]
		--k;
		dp[1][0] = 1;
		for (int i = 2; i <= n; i++) {
			dp[i][0] = 1;
			for (int j = 1; j <= min(i - 1, k); j++) {
				add(dp[i][j], 1ll * dp[i - 1][j] * (j + 1) % mod);
				add(dp[i][j], 1ll * dp[i - 1][j - 1] * (i - j) % mod);
			}
		}
		cout << dp[n][k];
	}
}

int main() {
	ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);

	if (fopen(Task".inp", "r")) {
		freopen(Task".inp", "r", stdin);
		freopen(Task".out", "w", stdout);
	}

	cin >> n >> k;
	// sub1::solve(); cout << '\n';
	// sub2::solve(); cout << '\n';
	sub3::solve();
}

Compilation message (stderr)

asceticism.cpp: In function 'int main()':
asceticism.cpp:101:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  101 |                 freopen(Task".inp", "r", stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
asceticism.cpp:102:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  102 |                 freopen(Task".out", "w", stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 20 / 20
• Subtask 3: 25 / 25
• Subtask 4: 0 / 51