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QOJ
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 |
---|---|---|---|---|---|---|---|---|---|
#397026 | #6736. Alice and Bob | VictorYuan# | AC ✓ | 103ms | 81848kb | C++14 | 1.1kb | 2024-04-23 15:45:45 | 2024-04-23 15:45:45 |
Judging History
answer
#include<bits/stdc++.h>
using namespace std;
const int mo = 998244353;
const int maxn = 1e7 + 7;
using ll = long long;
int fc[maxn],inv[maxn];
int qp(int a,int b) {
int ans = 1,base = a;
while(b != 0) {
if(b & 1) ans = 1ll * ans * base % mo;
base = 1ll * base * base % mo;
b >>= 1;
}
return ans % mo;
}
int main() {
int n;
cin >> n;
fc[0] = 1;
for(int i = 1;i <= n;i ++) fc[i] = 1ll * fc[i - 1] * i % mo;
// cerr << f1c[n - 1] << endl;
// ll ans1 = fc[n - 1] * (n + 1) / 4;
// int inv2 = (mo + 1) / 2;
// cerr << ans1 << " " << qp(2,mo - 2) << " " << (mo + 1) / 2 << endl;
// int x = n / 2 - 1;
// ll ans = 1ll * fc[n - 1] * (n + 1) % mo * qp(x,mo - 2) % mo;
ll ans = 0;
inv[n] = qp(fc[n],mo - 2);
for(int i = n - 1;i >= 0;i --) inv[i] = 1ll * inv[i + 1] * (i + 1) % mo;
auto A = [&](int n,int m) {
return 1ll * fc[n] * inv[n - m] % mo;
};
for(int i = 1;i <= n;i ++) {
if(i + i - 1 <= n) {
ans += 1ll * A(n - i,i - 1) * fc[n - i] % mo;
ans %= mo;
}
}
// cerr << tmp << endl;
cout << ans % mo << endl;
}
詳細信息
Test #1:
score: 100
Accepted
time: 1ms
memory: 5700kb
input:
1
output:
1
result:
ok 1 number(s): "1"
Test #2:
score: 0
Accepted
time: 1ms
memory: 5576kb
input:
2
output:
1
result:
ok 1 number(s): "1"
Test #3:
score: 0
Accepted
time: 1ms
memory: 5636kb
input:
10
output:
997920
result:
ok 1 number(s): "997920"
Test #4:
score: 0
Accepted
time: 1ms
memory: 5784kb
input:
100
output:
188898954
result:
ok 1 number(s): "188898954"
Test #5:
score: 0
Accepted
time: 1ms
memory: 5632kb
input:
4
output:
10
result:
ok 1 number(s): "10"
Test #6:
score: 0
Accepted
time: 1ms
memory: 5696kb
input:
8
output:
12336
result:
ok 1 number(s): "12336"
Test #7:
score: 0
Accepted
time: 1ms
memory: 5756kb
input:
16
output:
373118483
result:
ok 1 number(s): "373118483"
Test #8:
score: 0
Accepted
time: 1ms
memory: 5704kb
input:
32
output:
314585464
result:
ok 1 number(s): "314585464"
Test #9:
score: 0
Accepted
time: 1ms
memory: 5764kb
input:
64
output:
627827331
result:
ok 1 number(s): "627827331"
Test #10:
score: 0
Accepted
time: 1ms
memory: 5716kb
input:
128
output:
828497685
result:
ok 1 number(s): "828497685"
Test #11:
score: 0
Accepted
time: 1ms
memory: 5584kb
input:
256
output:
65697890
result:
ok 1 number(s): "65697890"
Test #12:
score: 0
Accepted
time: 0ms
memory: 5704kb
input:
512
output:
854187619
result:
ok 1 number(s): "854187619"
Test #13:
score: 0
Accepted
time: 0ms
memory: 5704kb
input:
1024
output:
513823539
result:
ok 1 number(s): "513823539"
Test #14:
score: 0
Accepted
time: 17ms
memory: 18728kb
input:
1361956
output:
617368199
result:
ok 1 number(s): "617368199"
Test #15:
score: 0
Accepted
time: 79ms
memory: 64396kb
input:
7579013
output:
827172636
result:
ok 1 number(s): "827172636"
Test #16:
score: 0
Accepted
time: 89ms
memory: 68956kb
input:
8145517
output:
710624331
result:
ok 1 number(s): "710624331"
Test #17:
score: 0
Accepted
time: 66ms
memory: 52356kb
input:
6140463
output:
707600568
result:
ok 1 number(s): "707600568"
Test #18:
score: 0
Accepted
time: 31ms
memory: 35300kb
input:
3515281
output:
698302413
result:
ok 1 number(s): "698302413"
Test #19:
score: 0
Accepted
time: 72ms
memory: 59896kb
input:
6969586
output:
69470392
result:
ok 1 number(s): "69470392"
Test #20:
score: 0
Accepted
time: 31ms
memory: 27924kb
input:
2888636
output:
433579983
result:
ok 1 number(s): "433579983"
Test #21:
score: 0
Accepted
time: 98ms
memory: 81828kb
input:
9999998
output:
758172780
result:
ok 1 number(s): "758172780"
Test #22:
score: 0
Accepted
time: 103ms
memory: 81848kb
input:
9999999
output:
605195495
result:
ok 1 number(s): "605195495"
Test #23:
score: 0
Accepted
time: 103ms
memory: 81776kb
input:
10000000
output:
866813682
result:
ok 1 number(s): "866813682"