QOJ.ac

QOJ

IDProblemSubmitterResultTimeMemoryLanguageFile sizeSubmit timeJudge time
#165713#6417. Classical Summation ProblemxuzhihaodedieAC ✓543ms19348kbC++141.1kb2023-09-05 21:07:402023-09-05 21:07:40

Judging History

你现在查看的是最新测评结果

  • [2023-09-05 21:07:40]
  • 评测
  • 测评结果:AC
  • 用时:543ms
  • 内存:19348kb
  • [2023-09-05 21:07:40]
  • 提交

answer

#include<bits/stdc++.h>
using namespace std;
#define int long long
//#define x first
//#define y second
#define PII pair<int,int>
const int N=1e6+10;
const int mod=998244353;
int fact[N],infact[N];
int qpow(int a,int b) {
	if(b==0) return 1;
	if(b&1) return a*qpow(a,b-1)%mod;
	else {
		int mul=qpow(a,b/2);
		return mul*mul%mod;
	}
}
void init() {
	fact[0]=1;
	for(int i=1;i<N;i++) fact[i]=fact[i-1]*i%mod;
	infact[N-1]=qpow(fact[N-1],mod-2);
	for(int i=N-2;i>=0;i--) infact[i]=infact[i+1]*(i+1)%mod;
} 
int c(int n,int m) {
	if(n<m) return 0;
	return fact[n]*infact[m]%mod*infact[n-m]%mod;
}

void solve() {
	int n,k;
	cin>>n>>k;
	int ans=0;
	if(k%2==1) {
		cout<<(n+1)*qpow(2,mod-2)%mod*qpow(n,k)%mod<<endl;
	} else {
		int ans=(n+1)*qpow(2,mod-2)%mod;
		for(int i=1;i<=n;i++) {
			ans=(ans-qpow(i,k/2)*qpow(n-i,k/2)%mod*c(k,k/2)%mod*qpow(qpow(n,k),mod-2)%mod*qpow(2,mod-2)%mod+mod)%mod;
		}
		ans=ans*qpow(n,k)%mod;
		cout<<ans<<endl;
	}
}
signed main() {
	int T=1;
	//cin>>T;
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	init();
	while(T--) {
		solve();
	}
}

Details

Tip: Click on the bar to expand more detailed information

Test #1:

score: 100
Accepted
time: 11ms
memory: 19268kb

input:

3 2

output:

14

result:

ok 1 number(s): "14"

Test #2:

score: 0
Accepted
time: 5ms
memory: 19288kb

input:

5 3

output:

375

result:

ok 1 number(s): "375"

Test #3:

score: 0
Accepted
time: 11ms
memory: 19284kb

input:

2 2

output:

5

result:

ok 1 number(s): "5"

Test #4:

score: 0
Accepted
time: 4ms
memory: 19228kb

input:

10 9

output:

508778235

result:

ok 1 number(s): "508778235"

Test #5:

score: 0
Accepted
time: 7ms
memory: 19276kb

input:

69 3

output:

11497815

result:

ok 1 number(s): "11497815"

Test #6:

score: 0
Accepted
time: 11ms
memory: 19264kb

input:

994 515

output:

33689623

result:

ok 1 number(s): "33689623"

Test #7:

score: 0
Accepted
time: 12ms
memory: 19340kb

input:

4476 6182

output:

114894183

result:

ok 1 number(s): "114894183"

Test #8:

score: 0
Accepted
time: 11ms
memory: 19220kb

input:

58957 12755

output:

932388891

result:

ok 1 number(s): "932388891"

Test #9:

score: 0
Accepted
time: 107ms
memory: 19344kb

input:

218138 28238

output:

392861201

result:

ok 1 number(s): "392861201"

Test #10:

score: 0
Accepted
time: 325ms
memory: 19348kb

input:

644125 316810

output:

420621854

result:

ok 1 number(s): "420621854"

Test #11:

score: 0
Accepted
time: 323ms
memory: 19292kb

input:

612914 505428

output:

973686286

result:

ok 1 number(s): "973686286"

Test #12:

score: 0
Accepted
time: 6ms
memory: 19272kb

input:

998216 938963

output:

251335926

result:

ok 1 number(s): "251335926"

Test #13:

score: 0
Accepted
time: 12ms
memory: 19280kb

input:

990516 996933

output:

549551960

result:

ok 1 number(s): "549551960"

Test #14:

score: 0
Accepted
time: 543ms
memory: 19276kb

input:

999019 999012

output:

637189128

result:

ok 1 number(s): "637189128"

Test #15:

score: 0
Accepted
time: 508ms
memory: 19344kb

input:

999928 999950

output:

185229465

result:

ok 1 number(s): "185229465"

Test #16:

score: 0
Accepted
time: 7ms
memory: 19284kb

input:

999999 999999

output:

384164916

result:

ok 1 number(s): "384164916"

Test #17:

score: 0
Accepted
time: 477ms
memory: 19332kb

input:

999999 1000000

output:

696165930

result:

ok 1 number(s): "696165930"

Test #18:

score: 0
Accepted
time: 12ms
memory: 19224kb

input:

1000000 999999

output:

219071706

result:

ok 1 number(s): "219071706"

Test #19:

score: 0
Accepted
time: 478ms
memory: 19268kb

input:

1000000 1000000

output:

128206597

result:

ok 1 number(s): "128206597"

Test #20:

score: 0
Accepted
time: 7ms
memory: 19272kb

input:

2 10

output:

1410

result:

ok 1 number(s): "1410"

Test #21:

score: 0
Accepted
time: 11ms
memory: 19208kb

input:

84 16

output:

297627153

result:

ok 1 number(s): "297627153"

Test #22:

score: 0
Accepted
time: 11ms
memory: 19216kb

input:

643 800

output:

489237163

result:

ok 1 number(s): "489237163"

Test #23:

score: 0
Accepted
time: 10ms
memory: 19280kb

input:

9903 880

output:

595167333

result:

ok 1 number(s): "595167333"

Test #24:

score: 0
Accepted
time: 50ms
memory: 19292kb

input:

97446 89750

output:

410205549

result:

ok 1 number(s): "410205549"

Test #25:

score: 0
Accepted
time: 110ms
memory: 19216kb

input:

186460 646474

output:

32638530

result:

ok 1 number(s): "32638530"

Test #26:

score: 0
Accepted
time: 270ms
memory: 19212kb

input:

508940 244684

output:

598321755

result:

ok 1 number(s): "598321755"

Test #27:

score: 0
Accepted
time: 307ms
memory: 19272kb

input:

583646 557758

output:

858695621

result:

ok 1 number(s): "858695621"

Test #28:

score: 0
Accepted
time: 486ms
memory: 19276kb

input:

969610 992608

output:

256683498

result:

ok 1 number(s): "256683498"

Test #29:

score: 0
Accepted
time: 516ms
memory: 19336kb

input:

995106 996434

output:

411791999

result:

ok 1 number(s): "411791999"

Test #30:

score: 0
Accepted
time: 491ms
memory: 19256kb

input:

999961 999872

output:

61222370

result:

ok 1 number(s): "61222370"

Test #31:

score: 0
Accepted
time: 521ms
memory: 19340kb

input:

999977 999908

output:

831096762

result:

ok 1 number(s): "831096762"

Test #32:

score: 0
Accepted
time: 541ms
memory: 19216kb

input:

999992 999998

output:

562977678

result:

ok 1 number(s): "562977678"

Test #33:

score: 0
Accepted
time: 244ms
memory: 19348kb

input:

1000000 2

output:

118436113

result:

ok 1 number(s): "118436113"

Test #34:

score: 0
Accepted
time: 7ms
memory: 19272kb

input:

2 1000000

output:

298823641

result:

ok 1 number(s): "298823641"