QOJ.ac
QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#412588 | #6736. Alice and Bob | XiaoretaW | TL | 971ms | 64884kb | C++20 | 1.4kb | 2024-05-16 16:19:44 | 2024-05-16 16:19:45 |
Judging History
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;
for (; b; b /= 2, a = 1LL * a * a % mod) {
if (b % 2) {
res = 1LL * res * a % mod;
}
}
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;
} else break;
}
cout << ans << '\n';
return 0;
}
Details
Tip: Click on the bar to expand more detailed information
Test #1:
score: 100
Accepted
time: 1ms
memory: 5600kb
input:
1
output:
1
result:
ok 1 number(s): "1"
Test #2:
score: 0
Accepted
time: 1ms
memory: 5592kb
input:
2
output:
1
result:
ok 1 number(s): "1"
Test #3:
score: 0
Accepted
time: 1ms
memory: 5680kb
input:
10
output:
997920
result:
ok 1 number(s): "997920"
Test #4:
score: 0
Accepted
time: 1ms
memory: 5684kb
input:
100
output:
188898954
result:
ok 1 number(s): "188898954"
Test #5:
score: 0
Accepted
time: 1ms
memory: 5620kb
input:
4
output:
10
result:
ok 1 number(s): "10"
Test #6:
score: 0
Accepted
time: 1ms
memory: 5672kb
input:
8
output:
12336
result:
ok 1 number(s): "12336"
Test #7:
score: 0
Accepted
time: 1ms
memory: 5748kb
input:
16
output:
373118483
result:
ok 1 number(s): "373118483"
Test #8:
score: 0
Accepted
time: 1ms
memory: 5656kb
input:
32
output:
314585464
result:
ok 1 number(s): "314585464"
Test #9:
score: 0
Accepted
time: 0ms
memory: 5656kb
input:
64
output:
627827331
result:
ok 1 number(s): "627827331"
Test #10:
score: 0
Accepted
time: 1ms
memory: 5664kb
input:
128
output:
828497685
result:
ok 1 number(s): "828497685"
Test #11:
score: 0
Accepted
time: 1ms
memory: 5748kb
input:
256
output:
65697890
result:
ok 1 number(s): "65697890"
Test #12:
score: 0
Accepted
time: 1ms
memory: 5748kb
input:
512
output:
854187619
result:
ok 1 number(s): "854187619"
Test #13:
score: 0
Accepted
time: 1ms
memory: 5732kb
input:
1024
output:
513823539
result:
ok 1 number(s): "513823539"
Test #14:
score: 0
Accepted
time: 173ms
memory: 19140kb
input:
1361956
output:
617368199
result:
ok 1 number(s): "617368199"
Test #15:
score: 0
Accepted
time: 971ms
memory: 64884kb
input:
7579013
output:
827172636
result:
ok 1 number(s): "827172636"
Test #16:
score: -100
Time Limit Exceeded
input:
8145517
output:
710624331