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ID题目提交者结果用时内存语言文件大小提交时间测评时间
#412578#6736. Alice and BobXiaoretaWTL 960ms64084kbC++201.4kb2024-05-16 16:15:402024-05-16 16:15:41

Judging History

你现在查看的是最新测评结果

  • [2024-05-16 16:15:41]
  • 评测
  • 测评结果:TL
  • 用时:960ms
  • 内存:64084kb
  • [2024-05-16 16:15:40]
  • 提交

answer

#pragma GCC optimize("O3,unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int mod = 998244353;
const int N = 1e7 + 1;
int fact[N], infact[N];
int power(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;
}
void Init(int n) {
    fact[0] = 1;
    infact[0] = 1;
    for (int i = 1; i <= n; i++) {
        fact[i] = 1ll * fact[i - 1] * i % mod;
        infact[i] = 1ll * infact[i - 1] * power(i, mod - 2) % mod;
    }
}
int C(int a, int b) {
    return 1ll * fact[a] * infact[b] % mod * infact[a - b] % mod;
}

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);    
    
    int n; cin >> n;
    Init(n);
    ll ans = 0;
    for (int i = 1; i <= n; i++) {
        if (i - 1 <= n - i) {
            // ans = (ans + 1ll * fact[i - 1] * C(n - i, i - 1) % mod * fact[n - i] % mod) % mod;
            // ll res = 1;
            // for (int j = n - 2 * i + 2; j <= n - i; j++) res = res * j % mod;
            // cout << "range: " << n - 2 * i + 2 << ' ' << n - i << '\n';
            // ans = (ans + 1ll * fact[n - i] * res % mod) % mod;
            ans = (ans + 1ll * fact[n - i] * fact[n - i] % mod * infact[n - 2 * i + 1] % mod) % mod;
        }
    }
    cout << ans << '\n';

    return 0;
}

详细

Test #1:

score: 100
Accepted
time: 1ms
memory: 5656kb

input:

1

output:

1

result:

ok 1 number(s): "1"

Test #2:

score: 0
Accepted
time: 0ms
memory: 5532kb

input:

2

output:

1

result:

ok 1 number(s): "1"

Test #3:

score: 0
Accepted
time: 1ms
memory: 5708kb

input:

10

output:

997920

result:

ok 1 number(s): "997920"

Test #4:

score: 0
Accepted
time: 0ms
memory: 5636kb

input:

100

output:

188898954

result:

ok 1 number(s): "188898954"

Test #5:

score: 0
Accepted
time: 1ms
memory: 5708kb

input:

4

output:

10

result:

ok 1 number(s): "10"

Test #6:

score: 0
Accepted
time: 1ms
memory: 5476kb

input:

8

output:

12336

result:

ok 1 number(s): "12336"

Test #7:

score: 0
Accepted
time: 1ms
memory: 5484kb

input:

16

output:

373118483

result:

ok 1 number(s): "373118483"

Test #8:

score: 0
Accepted
time: 1ms
memory: 5476kb

input:

32

output:

314585464

result:

ok 1 number(s): "314585464"

Test #9:

score: 0
Accepted
time: 0ms
memory: 5584kb

input:

64

output:

627827331

result:

ok 1 number(s): "627827331"

Test #10:

score: 0
Accepted
time: 1ms
memory: 5660kb

input:

128

output:

828497685

result:

ok 1 number(s): "828497685"

Test #11:

score: 0
Accepted
time: 1ms
memory: 5484kb

input:

256

output:

65697890

result:

ok 1 number(s): "65697890"

Test #12:

score: 0
Accepted
time: 1ms
memory: 5604kb

input:

512

output:

854187619

result:

ok 1 number(s): "854187619"

Test #13:

score: 0
Accepted
time: 1ms
memory: 5584kb

input:

1024

output:

513823539

result:

ok 1 number(s): "513823539"

Test #14:

score: 0
Accepted
time: 175ms
memory: 15384kb

input:

1361956

output:

617368199

result:

ok 1 number(s): "617368199"

Test #15:

score: 0
Accepted
time: 960ms
memory: 64084kb

input:

7579013

output:

827172636

result:

ok 1 number(s): "827172636"

Test #16:

score: -100
Time Limit Exceeded

input:

8145517

output:

710624331

result: