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IDProblemSubmitterResultTimeMemoryLanguageFile sizeSubmit timeJudge time
#153631#6417. Classical Summation Problem275307894aAC ✓125ms19672kbC++141.4kb2023-08-30 15:10:492023-08-30 15:10:49

Judging History

你现在查看的是最新测评结果

  • [2023-08-30 15:10:49]
  • 评测
  • 测评结果:AC
  • 用时:125ms
  • 内存:19672kb
  • [2023-08-30 15:10:49]
  • 提交

answer

#include<bits/stdc++.h>
#define Gc() getchar() 
#define Me(x,y) memset(x,y,sizeof(x))
#define Mc(x,y) memcpy(x,y,sizeof(x))
#define d(x,y) ((m)*(x-1)+(y))
#define R(n) (rnd()%(n)+1)
#define Pc(x) putchar(x)
#define LB lower_bound
#define UB upper_bound
#define fi first
#define se second
using namespace std;using ll=long long;using db=double;using lb=long db;using ui=unsigned;using ull=unsigned long long;using pii=pair<int,int>;using LL=__int128;
const int N=1e6+5,M=N*40+5,K=600+5,mod=998244353,Mod=mod-1;const db eps=1e-9;const ll INF=1e18+7;mt19937 rnd(time(0));
int n,m,k;ll frc[N],inv[N];
ll mpow(ll x,int y=mod-2){ll ans=1;while(y) y&1&&(ans=ans*x%mod),y>>=1,x=x*x%mod;return ans;}
ll C(int x,int y){return frc[x]*inv[y]%mod*inv[x-y]%mod;}
void Solve(){
	int i,j;scanf("%d%d",&n,&k);
	inv[1]=1;for(i=2;i<=k;i++) inv[i]=(mod-inv[mod%i])*(mod/i)%mod;
	for(frc[0]=inv[0]=i=1;i<=k;i++) frc[i]=frc[i-1]*i%mod,inv[i]=inv[i-1]*inv[i]%mod;
	// ll ans=0;
	// for(i=1;i<=n;i++){
	// 	for(j=0;j<=(k-1)/2;j++) ans+=C(k,j)*mpow(i-1,j)%mod*mpow(n-i+1,k-j)%mod;
	// }
	ll ans=mpow(n,k)*(n+1)%mod;
	if(k%2==0){
		for(i=1;i<=n+1;i++) ans-=C(k,k/2)*mpow(i-1,k/2)%mod*mpow(n-i+1,k/2)%mod;
	}
	// for(i=1;i<=n;i++) ans+=mpow(n,k);
	printf("%lld\n",(ans%mod+mod)*inv[2]%mod);
}
int main(){
	int t;
	// scanf("%d",&t);
	t=1;
	while(t--) Solve();
	cerr<<clock()*1.0/CLOCKS_PER_SEC<<'\n';
}


Details

Tip: Click on the bar to expand more detailed information

Test #1:

score: 100
Accepted
time: 1ms
memory: 6032kb

input:

3 2

output:

14

result:

ok 1 number(s): "14"

Test #2:

score: 0
Accepted
time: 1ms
memory: 6080kb

input:

5 3

output:

375

result:

ok 1 number(s): "375"

Test #3:

score: 0
Accepted
time: 1ms
memory: 6084kb

input:

2 2

output:

5

result:

ok 1 number(s): "5"

Test #4:

score: 0
Accepted
time: 1ms
memory: 6096kb

input:

10 9

output:

508778235

result:

ok 1 number(s): "508778235"

Test #5:

score: 0
Accepted
time: 1ms
memory: 6080kb

input:

69 3

output:

11497815

result:

ok 1 number(s): "11497815"

Test #6:

score: 0
Accepted
time: 1ms
memory: 6092kb

input:

994 515

output:

33689623

result:

ok 1 number(s): "33689623"

Test #7:

score: 0
Accepted
time: 0ms
memory: 6128kb

input:

4476 6182

output:

114894183

result:

ok 1 number(s): "114894183"

Test #8:

score: 0
Accepted
time: 1ms
memory: 6048kb

input:

58957 12755

output:

932388891

result:

ok 1 number(s): "932388891"

Test #9:

score: 0
Accepted
time: 18ms
memory: 6300kb

input:

218138 28238

output:

392861201

result:

ok 1 number(s): "392861201"

Test #10:

score: 0
Accepted
time: 63ms
memory: 14148kb

input:

644125 316810

output:

420621854

result:

ok 1 number(s): "420621854"

Test #11:

score: 0
Accepted
time: 67ms
memory: 16056kb

input:

612914 505428

output:

973686286

result:

ok 1 number(s): "973686286"

Test #12:

score: 0
Accepted
time: 10ms
memory: 19616kb

input:

998216 938963

output:

251335926

result:

ok 1 number(s): "251335926"

Test #13:

score: 0
Accepted
time: 11ms
memory: 19624kb

input:

990516 996933

output:

549551960

result:

ok 1 number(s): "549551960"

Test #14:

score: 0
Accepted
time: 114ms
memory: 19668kb

input:

999019 999012

output:

637189128

result:

ok 1 number(s): "637189128"

Test #15:

score: 0
Accepted
time: 125ms
memory: 19596kb

input:

999928 999950

output:

185229465

result:

ok 1 number(s): "185229465"

Test #16:

score: 0
Accepted
time: 11ms
memory: 19588kb

input:

999999 999999

output:

384164916

result:

ok 1 number(s): "384164916"

Test #17:

score: 0
Accepted
time: 113ms
memory: 19600kb

input:

999999 1000000

output:

696165930

result:

ok 1 number(s): "696165930"

Test #18:

score: 0
Accepted
time: 7ms
memory: 19652kb

input:

1000000 999999

output:

219071706

result:

ok 1 number(s): "219071706"

Test #19:

score: 0
Accepted
time: 112ms
memory: 19664kb

input:

1000000 1000000

output:

128206597

result:

ok 1 number(s): "128206597"

Test #20:

score: 0
Accepted
time: 0ms
memory: 6080kb

input:

2 10

output:

1410

result:

ok 1 number(s): "1410"

Test #21:

score: 0
Accepted
time: 1ms
memory: 6084kb

input:

84 16

output:

297627153

result:

ok 1 number(s): "297627153"

Test #22:

score: 0
Accepted
time: 1ms
memory: 6036kb

input:

643 800

output:

489237163

result:

ok 1 number(s): "489237163"

Test #23:

score: 0
Accepted
time: 1ms
memory: 6128kb

input:

9903 880

output:

595167333

result:

ok 1 number(s): "595167333"

Test #24:

score: 0
Accepted
time: 11ms
memory: 8840kb

input:

97446 89750

output:

410205549

result:

ok 1 number(s): "410205549"

Test #25:

score: 0
Accepted
time: 24ms
memory: 18692kb

input:

186460 646474

output:

32638530

result:

ok 1 number(s): "32638530"

Test #26:

score: 0
Accepted
time: 54ms
memory: 10608kb

input:

508940 244684

output:

598321755

result:

ok 1 number(s): "598321755"

Test #27:

score: 0
Accepted
time: 61ms
memory: 14904kb

input:

583646 557758

output:

858695621

result:

ok 1 number(s): "858695621"

Test #28:

score: 0
Accepted
time: 113ms
memory: 19608kb

input:

969610 992608

output:

256683498

result:

ok 1 number(s): "256683498"

Test #29:

score: 0
Accepted
time: 120ms
memory: 19652kb

input:

995106 996434

output:

411791999

result:

ok 1 number(s): "411791999"

Test #30:

score: 0
Accepted
time: 111ms
memory: 19672kb

input:

999961 999872

output:

61222370

result:

ok 1 number(s): "61222370"

Test #31:

score: 0
Accepted
time: 122ms
memory: 19664kb

input:

999977 999908

output:

831096762

result:

ok 1 number(s): "831096762"

Test #32:

score: 0
Accepted
time: 123ms
memory: 19600kb

input:

999992 999998

output:

562977678

result:

ok 1 number(s): "562977678"

Test #33:

score: 0
Accepted
time: 3ms
memory: 6120kb

input:

1000000 2

output:

118436113

result:

ok 1 number(s): "118436113"

Test #34:

score: 0
Accepted
time: 11ms
memory: 19660kb

input:

2 1000000

output:

298823641

result:

ok 1 number(s): "298823641"