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QOJ

IDProblemSubmitterResultTimeMemoryLanguageFile sizeSubmit timeJudge time
#132676#6736. Alice and Bobde_sousa#AC ✓159ms81756kbC++171.8kb2023-07-31 01:15:552023-07-31 01:15:59

Judging History

你现在查看的是最新测评结果

  • [2023-08-10 23:21:45]
  • System Update: QOJ starts to keep a history of the judgings of all the submissions.
  • [2023-07-31 01:15:59]
  • 评测
  • 测评结果:AC
  • 用时:159ms
  • 内存:81756kb
  • [2023-07-31 01:15:55]
  • 提交

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;
}

Details

Tip: Click on the bar to expand more detailed information

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"