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QOJ
ID | 题目 | 提交者 | 结果 | 用时 | 内存 | 语言 | 文件大小 | 提交时间 | 测评时间 |
---|---|---|---|---|---|---|---|---|---|
#165713 | #6417. Classical Summation Problem | xuzhihaodedie | AC ✓ | 543ms | 19348kb | C++14 | 1.1kb | 2023-09-05 21:07:40 | 2023-09-05 21:07:40 |
Judging History
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();
}
}
详细
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"