QOJ.ac
QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#153631 | #6417. Classical Summation Problem | 275307894a | AC ✓ | 125ms | 19672kb | C++14 | 1.4kb | 2023-08-30 15:10:49 | 2023-08-30 15:10:49 |
Judging History
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
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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"