QOJ.ac

QOJ

IDProblemSubmitterResultTimeMemoryLanguageFile sizeSubmit timeJudge time
#218518#6736. Alice and BobFr1nGeLove#TL 960ms64400kbC++20923b2023-10-18 14:25:392023-10-18 14:25:39

Judging History

你现在查看的是最新测评结果

  • [2023-10-18 14:25:39]
  • 评测
  • 测评结果:TL
  • 用时:960ms
  • 内存:64400kb
  • [2023-10-18 14:25:39]
  • 提交

answer

#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>

using namespace std;
using i64 = long long;

constexpr int N = 1E7 + 10, mod = 998244353;

int fac[N], invfac[N];

int qmi(int a, int b) {
	int res = 1;
	while (b) {
		if (b & 1) {
			res = (1LL * res * a) % mod;
		}
		a = (1LL * a * a) % mod;
		b >>= 1;
	}
	return res;
}

int main() {
	std::ios::sync_with_stdio(false);
	std::cin.tie(nullptr);

	int n;
	cin >> n;
	fac[0] = invfac[0] = 1;
	for (int i = 1; i <= n; ++i) {
		fac[i] = (1LL * fac[i - 1] * i) % mod;
		invfac[i] = (1LL * invfac[i - 1] * qmi(i, mod - 2)) % mod;
	}

	int ans = 0;
	for (int i = 1; i <= n; ++i) {
		if (i - 1 > n - i) break;
		int t;
		if (i - 1 == 0) {
			t = fac[n - i];
		} else {
			t = (1LL * (1LL * fac[n - i] * invfac[n - 2 * i + 1] % mod) * (fac[n - i])) % mod;
		}
		ans = (1LL * ans + t) % mod;
	}
	cout << ans << "\n";
	return 0;
}

Details

Tip: Click on the bar to expand more detailed information

Test #1:

score: 100
Accepted
time: 1ms
memory: 5652kb

input:

1

output:

1

result:

ok 1 number(s): "1"

Test #2:

score: 0
Accepted
time: 1ms
memory: 5672kb

input:

2

output:

1

result:

ok 1 number(s): "1"

Test #3:

score: 0
Accepted
time: 0ms
memory: 5668kb

input:

10

output:

997920

result:

ok 1 number(s): "997920"

Test #4:

score: 0
Accepted
time: 0ms
memory: 5664kb

input:

100

output:

188898954

result:

ok 1 number(s): "188898954"

Test #5:

score: 0
Accepted
time: 1ms
memory: 5664kb

input:

4

output:

10

result:

ok 1 number(s): "10"

Test #6:

score: 0
Accepted
time: 0ms
memory: 5596kb

input:

8

output:

12336

result:

ok 1 number(s): "12336"

Test #7:

score: 0
Accepted
time: 1ms
memory: 5628kb

input:

16

output:

373118483

result:

ok 1 number(s): "373118483"

Test #8:

score: 0
Accepted
time: 1ms
memory: 5624kb

input:

32

output:

314585464

result:

ok 1 number(s): "314585464"

Test #9:

score: 0
Accepted
time: 1ms
memory: 5752kb

input:

64

output:

627827331

result:

ok 1 number(s): "627827331"

Test #10:

score: 0
Accepted
time: 1ms
memory: 5600kb

input:

128

output:

828497685

result:

ok 1 number(s): "828497685"

Test #11:

score: 0
Accepted
time: 1ms
memory: 5664kb

input:

256

output:

65697890

result:

ok 1 number(s): "65697890"

Test #12:

score: 0
Accepted
time: 1ms
memory: 5684kb

input:

512

output:

854187619

result:

ok 1 number(s): "854187619"

Test #13:

score: 0
Accepted
time: 1ms
memory: 5620kb

input:

1024

output:

513823539

result:

ok 1 number(s): "513823539"

Test #14:

score: 0
Accepted
time: 170ms
memory: 15312kb

input:

1361956

output:

617368199

result:

ok 1 number(s): "617368199"

Test #15:

score: 0
Accepted
time: 960ms
memory: 64400kb

input:

7579013

output:

827172636

result:

ok 1 number(s): "827172636"

Test #16:

score: -100
Time Limit Exceeded

input:

8145517

output:

710624331

result: