QOJ.ac
QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#411869 | #6736. Alice and Bob | xiaodaiyang# | AC ✓ | 177ms | 394492kb | C++14 | 2.0kb | 2024-05-15 20:57:32 | 2024-05-15 20:57:32 |
Judging History
answer
#include <iostream>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <random>
#include <climits>
#include <unordered_set>
#include <unordered_map>
#include <bitset>
#include <iomanip>
using namespace std;
#define endl '\n'
typedef long long ll;
#define int long long
typedef __int128_t int128;
typedef pair<int, int> PII;
typedef pair<PII, int> PIII;
const int INF = 0x3f3f3f3f, mod = 998244353;
mt19937 rng(time(0));
#define x first
#define y second
#define lowbit(x) ((x) & -(x))
//#define double long double
const int N = 10000010;
const int M = 10000000;
ll n, m;
ll fact[N], infact[N];
int qmi(int a, int k, int p)
{
int res = 1;
while(k)
{
if(k & 1) res = (ll)res * a % p;
k >>= 1;
a = (ll)a * a % p;
}
return res;
}
ll s[N]; //n个数的前缀积
ll sv[N]; //n个数的前缀积的逆元
ll inv[N]; //第i个数的逆元
void solve() {
cin >> n;
ll ans = 0;
for (int i = 1; i <= n; i ++ ) {
if (n - i - (i - 1) >= 0) {
ans = (ans + fact[n - i] * infact[n - i - (i - 1)] % mod * fact[n - i] % mod) % mod;
}
}
cout << ans << endl;
}
signed main()
{
ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
// freopen("input.txt", "r", stdin);
// freopen("output.txt", "w", stdout);
int t = 1;
//cin >> t;
s[0] = 1;
for (int i = 1; i <= M; ++i) s[i] = s[i - 1] * i % mod;
sv[M] = qmi(s[M], mod - 2, mod);
// 当然这里也可以用 exgcd 来求逆元
for (int i = M; i >= 1; --i) sv[i - 1] = sv[i] * i % mod;
for (int i = 1; i <= M; ++i) inv[i] = sv[i] * s[i - 1] % mod;
fact[0] = infact[0] = 1;
for (int i = 1; i <= M; i ++ )
{
fact[i] = (ll)i * fact[i - 1] % mod;
infact[i] = (ll)infact[i - 1] * inv[i] % mod;
}
while(t--)
{
solve();
}
return 0;
}
Details
Tip: Click on the bar to expand more detailed information
Test #1:
score: 100
Accepted
time: 148ms
memory: 394236kb
input:
1
output:
1
result:
ok 1 number(s): "1"
Test #2:
score: 0
Accepted
time: 171ms
memory: 394360kb
input:
2
output:
1
result:
ok 1 number(s): "1"
Test #3:
score: 0
Accepted
time: 142ms
memory: 394440kb
input:
10
output:
997920
result:
ok 1 number(s): "997920"
Test #4:
score: 0
Accepted
time: 126ms
memory: 394440kb
input:
100
output:
188898954
result:
ok 1 number(s): "188898954"
Test #5:
score: 0
Accepted
time: 157ms
memory: 394296kb
input:
4
output:
10
result:
ok 1 number(s): "10"
Test #6:
score: 0
Accepted
time: 143ms
memory: 394252kb
input:
8
output:
12336
result:
ok 1 number(s): "12336"
Test #7:
score: 0
Accepted
time: 149ms
memory: 394420kb
input:
16
output:
373118483
result:
ok 1 number(s): "373118483"
Test #8:
score: 0
Accepted
time: 157ms
memory: 394300kb
input:
32
output:
314585464
result:
ok 1 number(s): "314585464"
Test #9:
score: 0
Accepted
time: 131ms
memory: 394416kb
input:
64
output:
627827331
result:
ok 1 number(s): "627827331"
Test #10:
score: 0
Accepted
time: 135ms
memory: 394300kb
input:
128
output:
828497685
result:
ok 1 number(s): "828497685"
Test #11:
score: 0
Accepted
time: 124ms
memory: 394364kb
input:
256
output:
65697890
result:
ok 1 number(s): "65697890"
Test #12:
score: 0
Accepted
time: 135ms
memory: 394436kb
input:
512
output:
854187619
result:
ok 1 number(s): "854187619"
Test #13:
score: 0
Accepted
time: 125ms
memory: 394436kb
input:
1024
output:
513823539
result:
ok 1 number(s): "513823539"
Test #14:
score: 0
Accepted
time: 138ms
memory: 394360kb
input:
1361956
output:
617368199
result:
ok 1 number(s): "617368199"
Test #15:
score: 0
Accepted
time: 158ms
memory: 394300kb
input:
7579013
output:
827172636
result:
ok 1 number(s): "827172636"
Test #16:
score: 0
Accepted
time: 172ms
memory: 394436kb
input:
8145517
output:
710624331
result:
ok 1 number(s): "710624331"
Test #17:
score: 0
Accepted
time: 152ms
memory: 394300kb
input:
6140463
output:
707600568
result:
ok 1 number(s): "707600568"
Test #18:
score: 0
Accepted
time: 135ms
memory: 394492kb
input:
3515281
output:
698302413
result:
ok 1 number(s): "698302413"
Test #19:
score: 0
Accepted
time: 149ms
memory: 394492kb
input:
6969586
output:
69470392
result:
ok 1 number(s): "69470392"
Test #20:
score: 0
Accepted
time: 144ms
memory: 394296kb
input:
2888636
output:
433579983
result:
ok 1 number(s): "433579983"
Test #21:
score: 0
Accepted
time: 160ms
memory: 394388kb
input:
9999998
output:
758172780
result:
ok 1 number(s): "758172780"
Test #22:
score: 0
Accepted
time: 177ms
memory: 394348kb
input:
9999999
output:
605195495
result:
ok 1 number(s): "605195495"
Test #23:
score: 0
Accepted
time: 156ms
memory: 394304kb
input:
10000000
output:
866813682
result:
ok 1 number(s): "866813682"