QOJ.ac
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 |
---|---|---|---|---|---|---|---|---|---|
#132676 | #6736. Alice and Bob | de_sousa# | AC ✓ | 159ms | 81756kb | C++17 | 1.8kb | 2023-07-31 01:15:55 | 2023-07-31 01:15:59 |
Judging History
answer
#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for (int i = a; i < b; i++)
#define all(x) begin(x),end(x)
#define trav(a, b) for (auto a : b)
#define lld long long
using i64 = long long;
const int N = 1e7 + 5;
int fac[N];
int invfac[N];
const int MOD = 998244353;
int mult(int a, int b) {
long long res = 1LL * a * b;
if (res >= MOD) res %= MOD;
return res;
}
int add(int a, int b) {
int res = a + b;
if (res >= MOD) res %= MOD;
return res;
}
int binpow(int a, int b) {
int res = 1;
int pw = a;
while (b) {
if (b & 1) res = mult(res, pw);
pw = mult(pw, pw);
b >>= 1;
}
return res;
}
int inv(int a) {
return binpow(a, MOD - 2);
}
int comb(int n, int i) {
if (i > n) return 0;
assert(i >= 0);
// cout << n << ' ' << i << '\n';
//cout << mult(fac[n], inv( mult(fac[i], fac[n - i]))) << '\n';
return mult(fac[n], mult(invfac[i], invfac[n - i]));
}
void solve() {
int n;
cin >> n;
// int per[n];
// rep(i,0,n)per[i]=i+1;
// int ans=0;
// do{
// bool b=true;
// rep(j,0,per[0]){
// if(per[j]<per[0])b=false;
// }
// ans+=b;
// }while(next_permutation(per,per+n));
// cout<<ans<<"\n";
int res = 0;
for (int i = 1; i <= n; i++) {
int div = mult(fac[i-1],fac[n - i]);
res = add(res, mult( comb(n - i, i - 1), div ) );
//cout<<comb(n - i, i - 1)<<" "<< div <<" "<<mult( comb(n - i, i - 1), div )<<endl;
}
cout << res << '\n';
// cout << binpow(5, 6) << '\n';
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int tt = 1;
fac[0] = 1;
for (int i = 1; i < N; i++) {
fac[i] = mult(i, fac[i - 1]);
}
invfac[N-1]=inv(fac[N-1]);
for(int i=N-2;i>=0;i--){
invfac[i]=mult(i+1,invfac[i+1]);
}
// cin >> tt;
while (tt--) solve();
return 0;
}
詳細信息
Test #1:
score: 100
Accepted
time: 80ms
memory: 81660kb
input:
1
output:
1
result:
ok 1 number(s): "1"
Test #2:
score: 0
Accepted
time: 90ms
memory: 81656kb
input:
2
output:
1
result:
ok 1 number(s): "1"
Test #3:
score: 0
Accepted
time: 82ms
memory: 81584kb
input:
10
output:
997920
result:
ok 1 number(s): "997920"
Test #4:
score: 0
Accepted
time: 90ms
memory: 81756kb
input:
100
output:
188898954
result:
ok 1 number(s): "188898954"
Test #5:
score: 0
Accepted
time: 82ms
memory: 81704kb
input:
4
output:
10
result:
ok 1 number(s): "10"
Test #6:
score: 0
Accepted
time: 86ms
memory: 81584kb
input:
8
output:
12336
result:
ok 1 number(s): "12336"
Test #7:
score: 0
Accepted
time: 86ms
memory: 81680kb
input:
16
output:
373118483
result:
ok 1 number(s): "373118483"
Test #8:
score: 0
Accepted
time: 86ms
memory: 81544kb
input:
32
output:
314585464
result:
ok 1 number(s): "314585464"
Test #9:
score: 0
Accepted
time: 86ms
memory: 81704kb
input:
64
output:
627827331
result:
ok 1 number(s): "627827331"
Test #10:
score: 0
Accepted
time: 82ms
memory: 81600kb
input:
128
output:
828497685
result:
ok 1 number(s): "828497685"
Test #11:
score: 0
Accepted
time: 87ms
memory: 81540kb
input:
256
output:
65697890
result:
ok 1 number(s): "65697890"
Test #12:
score: 0
Accepted
time: 88ms
memory: 81588kb
input:
512
output:
854187619
result:
ok 1 number(s): "854187619"
Test #13:
score: 0
Accepted
time: 80ms
memory: 81724kb
input:
1024
output:
513823539
result:
ok 1 number(s): "513823539"
Test #14:
score: 0
Accepted
time: 87ms
memory: 81600kb
input:
1361956
output:
617368199
result:
ok 1 number(s): "617368199"
Test #15:
score: 0
Accepted
time: 135ms
memory: 81592kb
input:
7579013
output:
827172636
result:
ok 1 number(s): "827172636"
Test #16:
score: 0
Accepted
time: 136ms
memory: 81548kb
input:
8145517
output:
710624331
result:
ok 1 number(s): "710624331"
Test #17:
score: 0
Accepted
time: 122ms
memory: 81596kb
input:
6140463
output:
707600568
result:
ok 1 number(s): "707600568"
Test #18:
score: 0
Accepted
time: 105ms
memory: 81540kb
input:
3515281
output:
698302413
result:
ok 1 number(s): "698302413"
Test #19:
score: 0
Accepted
time: 132ms
memory: 81552kb
input:
6969586
output:
69470392
result:
ok 1 number(s): "69470392"
Test #20:
score: 0
Accepted
time: 105ms
memory: 81592kb
input:
2888636
output:
433579983
result:
ok 1 number(s): "433579983"
Test #21:
score: 0
Accepted
time: 155ms
memory: 81544kb
input:
9999998
output:
758172780
result:
ok 1 number(s): "758172780"
Test #22:
score: 0
Accepted
time: 159ms
memory: 81600kb
input:
9999999
output:
605195495
result:
ok 1 number(s): "605195495"
Test #23:
score: 0
Accepted
time: 150ms
memory: 81608kb
input:
10000000
output:
866813682
result:
ok 1 number(s): "866813682"