QOJ.ac
QOJ
| ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
|---|---|---|---|---|---|---|---|---|---|
| #155629 | #6417. Classical Summation Problem | Forever_Young# | WA | 1ms | 3540kb | C++14 | 830b | 2023-09-01 22:14:38 | 2023-09-01 22:14:38 |
Judging History
answer
#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
const LL mod = 998244353;
LL fastpo(LL x, LL n, LL mod) {
x %= mod;
LL res = 1;
while(n) {
if(n % 2 == 1) {
res = (res * x) % mod;
}
x = x * x % mod;
n /= 2;
}
return res;
}
int main() {
LL n, k;
cin >> n >> k;
LL inv2 = (mod + 1) / 2;
LL ans = 0;
if(k % 2 == 1) {
ans = fastpo(n, k, mod);
ans = (ans * (1 + n)) % mod;
ans = ans * inv2 % mod;
}else {
ans = fastpo(n, k, mod);
ans = (ans * (1 + n)) % mod;
ans = ans * inv2 % mod;
LL tmp = 0;
for(int j = 1; j <= n - 1; j++) {
tmp = tmp + fastpo(j, k / 2, mod) * fastpo(n - j, k / 2, mod);
tmp = tmp % mod;
}
//cout << ans << ' ' << tmp << endl;
ans = (ans - tmp) % mod;
ans = (ans + mod) % mod;
}
cout << ans << endl;
}
Details
Tip: Click on the bar to expand more detailed information
Test #1:
score: 100
Accepted
time: 1ms
memory: 3356kb
input:
3 2
output:
14
result:
ok 1 number(s): "14"
Test #2:
score: 0
Accepted
time: 1ms
memory: 3388kb
input:
5 3
output:
375
result:
ok 1 number(s): "375"
Test #3:
score: 0
Accepted
time: 1ms
memory: 3512kb
input:
2 2
output:
5
result:
ok 1 number(s): "5"
Test #4:
score: 0
Accepted
time: 1ms
memory: 3540kb
input:
10 9
output:
508778235
result:
ok 1 number(s): "508778235"
Test #5:
score: 0
Accepted
time: 1ms
memory: 3372kb
input:
69 3
output:
11497815
result:
ok 1 number(s): "11497815"
Test #6:
score: 0
Accepted
time: 1ms
memory: 3376kb
input:
994 515
output:
33689623
result:
ok 1 number(s): "33689623"
Test #7:
score: -100
Wrong Answer
time: 1ms
memory: 3352kb
input:
4476 6182
output:
654114565
result:
wrong answer 1st numbers differ - expected: '114894183', found: '654114565'