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QOJ

IDProblemSubmitterResultTimeMemoryLanguageFile sizeSubmit timeJudge time
#216648#6736. Alice and BobEunoiayAC ✓116ms159292kbC++201.0kb2023-10-15 20:46:182023-10-15 20:46:20

Judging History

你现在查看的是最新测评结果

  • [2023-10-15 20:46:20]
  • 评测
  • 测评结果:AC
  • 用时:116ms
  • 内存:159292kb
  • [2023-10-15 20:46:18]
  • 提交

answer

#include <bits/stdc++.h>

using namespace std;
using i64 = long long;

constexpr int P = 998244353;

i64 power(i64 a, i64 k) {
	i64 res = 1;
	for ( ; k; k >>= 1, a = a * a % P) {
		if (k & 1) {
			res = res * a % P;
		}
	}
	return res;
}

i64 get_inv(i64 x) {
	return power(x, P - 2);
}

void solve() {
	int n;
	cin >> n;

    vector<i64> fac(n + 1), inv_fac(n + 1);
    fac[0] = 1;
    for (int i = 1; i <= n; i++) {
        fac[i] = fac[i - 1] * i % P;
    }
    inv_fac[n] = power(fac[n], P - 2);
    for (int i = n; i; i--) {
        inv_fac[i - 1] = inv_fac[i] * i % P;
    }

	auto Perm = [&](int a, int b) -> i64 {
		if (a == b) {
			return fac[a];
		}
		if (a < b) {
			return 0;
		}
		return fac[a] * inv_fac[a - b] % P;
	};

    int ans = 0;
    for (int i = 1; i <= n; ++ i) {
    	ans += Perm(n - i, i - 1) * Perm(n - i, n - i) % P;
    	ans %= P;
    }
    cout << ans << "\n";
}	

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

	solve();

	return 0;
}

Details

Tip: Click on the bar to expand more detailed information

Test #1:

score: 100
Accepted
time: 1ms
memory: 3420kb

input:

1

output:

1

result:

ok 1 number(s): "1"

Test #2:

score: 0
Accepted
time: 0ms
memory: 3540kb

input:

2

output:

1

result:

ok 1 number(s): "1"

Test #3:

score: 0
Accepted
time: 0ms
memory: 3432kb

input:

10

output:

997920

result:

ok 1 number(s): "997920"

Test #4:

score: 0
Accepted
time: 0ms
memory: 3488kb

input:

100

output:

188898954

result:

ok 1 number(s): "188898954"

Test #5:

score: 0
Accepted
time: 0ms
memory: 3432kb

input:

4

output:

10

result:

ok 1 number(s): "10"

Test #6:

score: 0
Accepted
time: 0ms
memory: 3472kb

input:

8

output:

12336

result:

ok 1 number(s): "12336"

Test #7:

score: 0
Accepted
time: 0ms
memory: 3432kb

input:

16

output:

373118483

result:

ok 1 number(s): "373118483"

Test #8:

score: 0
Accepted
time: 1ms
memory: 3428kb

input:

32

output:

314585464

result:

ok 1 number(s): "314585464"

Test #9:

score: 0
Accepted
time: 0ms
memory: 3468kb

input:

64

output:

627827331

result:

ok 1 number(s): "627827331"

Test #10:

score: 0
Accepted
time: 0ms
memory: 3436kb

input:

128

output:

828497685

result:

ok 1 number(s): "828497685"

Test #11:

score: 0
Accepted
time: 0ms
memory: 3464kb

input:

256

output:

65697890

result:

ok 1 number(s): "65697890"

Test #12:

score: 0
Accepted
time: 0ms
memory: 3420kb

input:

512

output:

854187619

result:

ok 1 number(s): "854187619"

Test #13:

score: 0
Accepted
time: 0ms
memory: 3520kb

input:

1024

output:

513823539

result:

ok 1 number(s): "513823539"

Test #14:

score: 0
Accepted
time: 17ms
memory: 24400kb

input:

1361956

output:

617368199

result:

ok 1 number(s): "617368199"

Test #15:

score: 0
Accepted
time: 90ms
memory: 121476kb

input:

7579013

output:

827172636

result:

ok 1 number(s): "827172636"

Test #16:

score: 0
Accepted
time: 102ms
memory: 130388kb

input:

8145517

output:

710624331

result:

ok 1 number(s): "710624331"

Test #17:

score: 0
Accepted
time: 73ms
memory: 98956kb

input:

6140463

output:

707600568

result:

ok 1 number(s): "707600568"

Test #18:

score: 0
Accepted
time: 44ms
memory: 58056kb

input:

3515281

output:

698302413

result:

ok 1 number(s): "698302413"

Test #19:

score: 0
Accepted
time: 85ms
memory: 111972kb

input:

6969586

output:

69470392

result:

ok 1 number(s): "69470392"

Test #20:

score: 0
Accepted
time: 39ms
memory: 48116kb

input:

2888636

output:

433579983

result:

ok 1 number(s): "433579983"

Test #21:

score: 0
Accepted
time: 114ms
memory: 159280kb

input:

9999998

output:

758172780

result:

ok 1 number(s): "758172780"

Test #22:

score: 0
Accepted
time: 116ms
memory: 159176kb

input:

9999999

output:

605195495

result:

ok 1 number(s): "605195495"

Test #23:

score: 0
Accepted
time: 116ms
memory: 159292kb

input:

10000000

output:

866813682

result:

ok 1 number(s): "866813682"