QOJ.ac
QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#176258 | #6417. Classical Summation Problem | Liberty12619 | AC ✓ | 130ms | 19348kb | C++20 | 1.1kb | 2023-09-11 13:50:00 | 2023-09-11 13:50:00 |
Judging History
answer
#include <bits/stdc++.h>
#define x first
#define y second
#define int long long
using namespace std;
typedef pair<int,int> PII;
const int N = 1e6 + 10,INF=1e12,mod = 998244353;
int fact[N],infact[N];
int qmi(int a,int b)
{
int res=1;
while(b)
{
if(b&1) res=res*a%mod;
a=a*a%mod;
b>>=1;
}
return res;
}
void init()
{
fact[0]=infact[0]=1;
for(int i=1;i<N;i++)fact[i]=fact[i-1]*i%mod;
infact[N-1]=qmi(fact[N-1],mod-2);
for(int i=N-2;i>0;i--) infact[i]=infact[i+1]*(i+1)%mod;
}
int C(int a,int b)
{
if(a<b) return 0;
return fact[a]*infact[b]%mod*infact[a-b]%mod;
}
void solve()
{
int n,k;
cin>>n>>k;
if(k&1)
{
cout<<(n+1)*infact[2]%mod*qmi(n,k)%mod<<"\n";
return;
}
int res=0;
for(int i=1;i<n;i++) res+=qmi(i,k/2)*qmi(n-i,k/2)%mod*C(k,k/2)%mod;
res = ((n+1)*infact[2]%mod*qmi(n,k)%mod-res%mod*infact[2]%mod+mod)%mod;
cout<<res<<"\n";
}
signed main()
{
int T=1;
cin.tie(0)->sync_with_stdio(false);
//cin>>T;
init();
while(T--)
{
solve();
}
}
Details
Tip: Click on the bar to expand more detailed information
Test #1:
score: 100
Accepted
time: 3ms
memory: 19292kb
input:
3 2
output:
14
result:
ok 1 number(s): "14"
Test #2:
score: 0
Accepted
time: 7ms
memory: 19296kb
input:
5 3
output:
375
result:
ok 1 number(s): "375"
Test #3:
score: 0
Accepted
time: 11ms
memory: 19296kb
input:
2 2
output:
5
result:
ok 1 number(s): "5"
Test #4:
score: 0
Accepted
time: 3ms
memory: 19276kb
input:
10 9
output:
508778235
result:
ok 1 number(s): "508778235"
Test #5:
score: 0
Accepted
time: 7ms
memory: 19220kb
input:
69 3
output:
11497815
result:
ok 1 number(s): "11497815"
Test #6:
score: 0
Accepted
time: 11ms
memory: 19280kb
input:
994 515
output:
33689623
result:
ok 1 number(s): "33689623"
Test #7:
score: 0
Accepted
time: 7ms
memory: 19340kb
input:
4476 6182
output:
114894183
result:
ok 1 number(s): "114894183"
Test #8:
score: 0
Accepted
time: 7ms
memory: 19340kb
input:
58957 12755
output:
932388891
result:
ok 1 number(s): "932388891"
Test #9:
score: 0
Accepted
time: 18ms
memory: 19264kb
input:
218138 28238
output:
392861201
result:
ok 1 number(s): "392861201"
Test #10:
score: 0
Accepted
time: 73ms
memory: 19268kb
input:
644125 316810
output:
420621854
result:
ok 1 number(s): "420621854"
Test #11:
score: 0
Accepted
time: 80ms
memory: 19280kb
input:
612914 505428
output:
973686286
result:
ok 1 number(s): "973686286"
Test #12:
score: 0
Accepted
time: 11ms
memory: 19220kb
input:
998216 938963
output:
251335926
result:
ok 1 number(s): "251335926"
Test #13:
score: 0
Accepted
time: 3ms
memory: 19276kb
input:
990516 996933
output:
549551960
result:
ok 1 number(s): "549551960"
Test #14:
score: 0
Accepted
time: 129ms
memory: 19348kb
input:
999019 999012
output:
637189128
result:
ok 1 number(s): "637189128"
Test #15:
score: 0
Accepted
time: 130ms
memory: 19276kb
input:
999928 999950
output:
185229465
result:
ok 1 number(s): "185229465"
Test #16:
score: 0
Accepted
time: 7ms
memory: 19292kb
input:
999999 999999
output:
384164916
result:
ok 1 number(s): "384164916"
Test #17:
score: 0
Accepted
time: 120ms
memory: 19264kb
input:
999999 1000000
output:
696165930
result:
ok 1 number(s): "696165930"
Test #18:
score: 0
Accepted
time: 11ms
memory: 19280kb
input:
1000000 999999
output:
219071706
result:
ok 1 number(s): "219071706"
Test #19:
score: 0
Accepted
time: 116ms
memory: 19348kb
input:
1000000 1000000
output:
128206597
result:
ok 1 number(s): "128206597"
Test #20:
score: 0
Accepted
time: 7ms
memory: 19292kb
input:
2 10
output:
1410
result:
ok 1 number(s): "1410"
Test #21:
score: 0
Accepted
time: 3ms
memory: 19280kb
input:
84 16
output:
297627153
result:
ok 1 number(s): "297627153"
Test #22:
score: 0
Accepted
time: 3ms
memory: 19284kb
input:
643 800
output:
489237163
result:
ok 1 number(s): "489237163"
Test #23:
score: 0
Accepted
time: 8ms
memory: 19344kb
input:
9903 880
output:
595167333
result:
ok 1 number(s): "595167333"
Test #24:
score: 0
Accepted
time: 16ms
memory: 19288kb
input:
97446 89750
output:
410205549
result:
ok 1 number(s): "410205549"
Test #25:
score: 0
Accepted
time: 32ms
memory: 19228kb
input:
186460 646474
output:
32638530
result:
ok 1 number(s): "32638530"
Test #26:
score: 0
Accepted
time: 65ms
memory: 19276kb
input:
508940 244684
output:
598321755
result:
ok 1 number(s): "598321755"
Test #27:
score: 0
Accepted
time: 61ms
memory: 19340kb
input:
583646 557758
output:
858695621
result:
ok 1 number(s): "858695621"
Test #28:
score: 0
Accepted
time: 113ms
memory: 19344kb
input:
969610 992608
output:
256683498
result:
ok 1 number(s): "256683498"
Test #29:
score: 0
Accepted
time: 115ms
memory: 19296kb
input:
995106 996434
output:
411791999
result:
ok 1 number(s): "411791999"
Test #30:
score: 0
Accepted
time: 121ms
memory: 19288kb
input:
999961 999872
output:
61222370
result:
ok 1 number(s): "61222370"
Test #31:
score: 0
Accepted
time: 130ms
memory: 19284kb
input:
999977 999908
output:
831096762
result:
ok 1 number(s): "831096762"
Test #32:
score: 0
Accepted
time: 130ms
memory: 19316kb
input:
999992 999998
output:
562977678
result:
ok 1 number(s): "562977678"
Test #33:
score: 0
Accepted
time: 14ms
memory: 19208kb
input:
1000000 2
output:
118436113
result:
ok 1 number(s): "118436113"
Test #34:
score: 0
Accepted
time: 7ms
memory: 19292kb
input:
2 1000000
output:
298823641
result:
ok 1 number(s): "298823641"