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IDProblemSubmitterResultTimeMemoryLanguageFile sizeSubmit timeJudge time
#211910#6736. Alice and BobYFOQAC ✓345ms163260kbC++112.1kb2023-10-12 22:50:472023-10-12 22:50:48

Judging History

你现在查看的是最新测评结果

  • [2023-10-12 22:50:48]
  • 评测
  • 测评结果:AC
  • 用时:345ms
  • 内存:163260kb
  • [2023-10-12 22:50:47]
  • 提交

answer

#include<bits/stdc++.h>
#define ll long long

#define x first
#define y second
#define IO ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define pb(x) push_back(x)
#define endl '\n'
#define fix(x) cout << fixed << setprecision(x) ;
#pragma GCC optimize(2)

using namespace std;
typedef pair<int,int>PII;
typedef pair<double,double>PDD;
typedef pair<int,PII>PIP;
typedef pair<PII,int>PPI;
typedef vector<int>VI;
const int N =5e5+5;
const long long INF = 1e16;
int mod= 998244353;


ll a[10000001];
int kpow(int x,int n);
ll inv[10000001];
vector<int>p;
ll A(int n,int x){
//	cout<<n<<" "<<n-x<<endl;
//	cout<<a[n]<<" "<<a[n-x]<<endl;
	
	return a[n]*inv[n-x]%mod;
	//return a[n]*kpow(a[n-x],mod-2)%mod;
}
inline void Solve(){
	int n;
	cin>>n;
	memset(inv,-1,sizeof inv);
	a[0]=1;
	inv[1]=1;
	inv[0]=1;
	a[1]=1;
	for(int i=2;i<=n;i++){
	
		if(inv[i]==-1){
			p.pb(i);
			inv[i]=kpow(i,mod-2);	
		}
		
		for(auto j:p){
			if(j*i>n)break;
			inv[i*j]=inv[i]*inv[j]%mod;
			if(i%j==0)break;
		}
	}
	for(int i=1;i<=n;i++){
		a[i]=a[i-1]*i;
		a[i]%=mod;
		inv[i]*=inv[i-1];
		inv[i]%=mod;
	}
//	for(int i=1;i<=n;i++){
//		cout<<kpow(inv[i],mod-2)<<endl;
//	}
	ll res =0;
	for(int i=1;i<=n/2+1;++i){
		
		res+=A((n-i),i-1)*(a[n-i]);
	//	cout<<res<<endl;
		res%=mod;
	}
	cout<<res<<endl;
}
	

//1 0.75
signed main(){
//	IO
//	fix(16);

	int T=1;
//	cin>>T;
	for(int i=1;i<=T;i++){
	
	
		Solve();
	}
	return 0;
	
}

/*

*/

int lowbit(int n)
{
	return n&-n;
}

inline void read(int &x)
{
   int f=0;x=0;char c=getchar();
   while(c<'0'||c>'9')f|=c=='-',c=getchar();
   while(c>='0'&&c<='9')x=(x<<1)+(x<<3)+(c^48),c=getchar();
   x=f?-x:x;
}
inline void print(long long x)
{
    if(x<0){
        putchar('-');
        x=-x;
    }
    if(x>9) print(x/10);
    putchar(x%10+'0');
}

//ofstream out("file.txt");
//ifstream in("file.txt"); 
inline int kpow(int x,int y){
	if(y==0)return 1;
	if(x==0)return 0;
	long long res =1;
	long long p=x;
	for(int i=0;y>>i;++i){
		if((y>>i)&1){
			res*=p;
			res%=mod;
		}
		p*=p;
		p%=mod;
	}
	return res;
}

Details

Tip: Click on the bar to expand more detailed information

Test #1:

score: 100
Accepted
time: 0ms
memory: 82656kb

input:

1

output:

1

result:

ok 1 number(s): "1"

Test #2:

score: 0
Accepted
time: 0ms
memory: 82500kb

input:

2

output:

1

result:

ok 1 number(s): "1"

Test #3:

score: 0
Accepted
time: 0ms
memory: 82912kb

input:

10

output:

997920

result:

ok 1 number(s): "997920"

Test #4:

score: 0
Accepted
time: 0ms
memory: 83772kb

input:

100

output:

188898954

result:

ok 1 number(s): "188898954"

Test #5:

score: 0
Accepted
time: 7ms
memory: 83564kb

input:

4

output:

10

result:

ok 1 number(s): "10"

Test #6:

score: 0
Accepted
time: 3ms
memory: 83208kb

input:

8

output:

12336

result:

ok 1 number(s): "12336"

Test #7:

score: 0
Accepted
time: 0ms
memory: 82760kb

input:

16

output:

373118483

result:

ok 1 number(s): "373118483"

Test #8:

score: 0
Accepted
time: 0ms
memory: 82004kb

input:

32

output:

314585464

result:

ok 1 number(s): "314585464"

Test #9:

score: 0
Accepted
time: 4ms
memory: 82612kb

input:

64

output:

627827331

result:

ok 1 number(s): "627827331"

Test #10:

score: 0
Accepted
time: 3ms
memory: 83356kb

input:

128

output:

828497685

result:

ok 1 number(s): "828497685"

Test #11:

score: 0
Accepted
time: 0ms
memory: 81876kb

input:

256

output:

65697890

result:

ok 1 number(s): "65697890"

Test #12:

score: 0
Accepted
time: 3ms
memory: 82492kb

input:

512

output:

854187619

result:

ok 1 number(s): "854187619"

Test #13:

score: 0
Accepted
time: 7ms
memory: 83296kb

input:

1024

output:

513823539

result:

ok 1 number(s): "513823539"

Test #14:

score: 0
Accepted
time: 53ms
memory: 93996kb

input:

1361956

output:

617368199

result:

ok 1 number(s): "617368199"

Test #15:

score: 0
Accepted
time: 252ms
memory: 143260kb

input:

7579013

output:

827172636

result:

ok 1 number(s): "827172636"

Test #16:

score: 0
Accepted
time: 290ms
memory: 149812kb

input:

8145517

output:

710624331

result:

ok 1 number(s): "710624331"

Test #17:

score: 0
Accepted
time: 207ms
memory: 131456kb

input:

6140463

output:

707600568

result:

ok 1 number(s): "707600568"

Test #18:

score: 0
Accepted
time: 127ms
memory: 111780kb

input:

3515281

output:

698302413

result:

ok 1 number(s): "698302413"

Test #19:

score: 0
Accepted
time: 251ms
memory: 138592kb

input:

6969586

output:

69470392

result:

ok 1 number(s): "69470392"

Test #20:

score: 0
Accepted
time: 98ms
memory: 105932kb

input:

2888636

output:

433579983

result:

ok 1 number(s): "433579983"

Test #21:

score: 0
Accepted
time: 345ms
memory: 162016kb

input:

9999998

output:

758172780

result:

ok 1 number(s): "758172780"

Test #22:

score: 0
Accepted
time: 345ms
memory: 163260kb

input:

9999999

output:

605195495

result:

ok 1 number(s): "605195495"

Test #23:

score: 0
Accepted
time: 331ms
memory: 162528kb

input:

10000000

output:

866813682

result:

ok 1 number(s): "866813682"