QOJ.ac
QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#136386 | #6417. Classical Summation Problem | feeder1# | AC ✓ | 87ms | 19264kb | C++17 | 1.6kb | 2023-08-08 12:27:59 | 2023-08-08 12:28:02 |
Judging History
answer
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef tuple<int, int, int> tii;
typedef tuple<ll, ll, ll> tll;
typedef long double ld;
typedef vector<int> vi;
typedef vector<ll> vl;
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define nl "\n"
#define all(v) v.begin(),v.end()
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define sz(x) (int)(x).size()
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
const int maxn = 1e6 + 5;
const ll mod = 998244353;
ll fpow(int b, int p) {
ll res = 1;
while (p) {
if (p & 1) {
res = (ll) res * b % mod;
}
b = (ll) b * b % mod;
p >>= 1;
}
return res;
}
ll fac[maxn], ifac[maxn];
ll inv(ll a) {
return fpow(a, mod - 2);
}
ll ncr(ll a, ll b){
if (b > a) return 0;
return fac[a] * ifac[b] % mod * ifac[a-b] % mod;
}
void initfac(){
fac[0] = 1;
for (int i = 1; i < maxn; i++) fac[i] = fac[i-1] * i % mod;
ifac[maxn - 1] = inv(fac[maxn - 1]);
for (int i = maxn - 1; i >= 1; i--) ifac[i - 1] = ifac[i] * i % mod;
}
ll n, m, q, k, t, a, b, c;
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
initfac();
cin >> n >> k;
if (k % 2) {
cout << fpow(n, k) * inv(2) % mod * (n + 1) % mod;
} else {
ll ans = fpow(n, k) * (n + 1) % mod;
ll nck = ncr(k, k / 2);
k = k / 2;
for (ll i = 1; i <= n - 1; i++) {
ans = (ans - nck * fpow(i * (n - i) % mod, k)) % mod;
}
ans = (ans + mod) * inv(2) % mod;
cout << ans;
}
}
Details
Tip: Click on the bar to expand more detailed information
Test #1:
score: 100
Accepted
time: 6ms
memory: 19264kb
input:
3 2
output:
14
result:
ok 1 number(s): "14"
Test #2:
score: 0
Accepted
time: 4ms
memory: 19264kb
input:
5 3
output:
375
result:
ok 1 number(s): "375"
Test #3:
score: 0
Accepted
time: 12ms
memory: 19108kb
input:
2 2
output:
5
result:
ok 1 number(s): "5"
Test #4:
score: 0
Accepted
time: 12ms
memory: 19208kb
input:
10 9
output:
508778235
result:
ok 1 number(s): "508778235"
Test #5:
score: 0
Accepted
time: 8ms
memory: 19092kb
input:
69 3
output:
11497815
result:
ok 1 number(s): "11497815"
Test #6:
score: 0
Accepted
time: 4ms
memory: 19068kb
input:
994 515
output:
33689623
result:
ok 1 number(s): "33689623"
Test #7:
score: 0
Accepted
time: 6ms
memory: 19108kb
input:
4476 6182
output:
114894183
result:
ok 1 number(s): "114894183"
Test #8:
score: 0
Accepted
time: 8ms
memory: 19092kb
input:
58957 12755
output:
932388891
result:
ok 1 number(s): "932388891"
Test #9:
score: 0
Accepted
time: 19ms
memory: 19264kb
input:
218138 28238
output:
392861201
result:
ok 1 number(s): "392861201"
Test #10:
score: 0
Accepted
time: 47ms
memory: 19112kb
input:
644125 316810
output:
420621854
result:
ok 1 number(s): "420621854"
Test #11:
score: 0
Accepted
time: 56ms
memory: 19224kb
input:
612914 505428
output:
973686286
result:
ok 1 number(s): "973686286"
Test #12:
score: 0
Accepted
time: 11ms
memory: 19260kb
input:
998216 938963
output:
251335926
result:
ok 1 number(s): "251335926"
Test #13:
score: 0
Accepted
time: 11ms
memory: 19224kb
input:
990516 996933
output:
549551960
result:
ok 1 number(s): "549551960"
Test #14:
score: 0
Accepted
time: 84ms
memory: 19116kb
input:
999019 999012
output:
637189128
result:
ok 1 number(s): "637189128"
Test #15:
score: 0
Accepted
time: 82ms
memory: 19120kb
input:
999928 999950
output:
185229465
result:
ok 1 number(s): "185229465"
Test #16:
score: 0
Accepted
time: 11ms
memory: 19220kb
input:
999999 999999
output:
384164916
result:
ok 1 number(s): "384164916"
Test #17:
score: 0
Accepted
time: 86ms
memory: 19088kb
input:
999999 1000000
output:
696165930
result:
ok 1 number(s): "696165930"
Test #18:
score: 0
Accepted
time: 4ms
memory: 19092kb
input:
1000000 999999
output:
219071706
result:
ok 1 number(s): "219071706"
Test #19:
score: 0
Accepted
time: 86ms
memory: 19220kb
input:
1000000 1000000
output:
128206597
result:
ok 1 number(s): "128206597"
Test #20:
score: 0
Accepted
time: 11ms
memory: 19096kb
input:
2 10
output:
1410
result:
ok 1 number(s): "1410"
Test #21:
score: 0
Accepted
time: 12ms
memory: 19072kb
input:
84 16
output:
297627153
result:
ok 1 number(s): "297627153"
Test #22:
score: 0
Accepted
time: 5ms
memory: 19264kb
input:
643 800
output:
489237163
result:
ok 1 number(s): "489237163"
Test #23:
score: 0
Accepted
time: 12ms
memory: 19064kb
input:
9903 880
output:
595167333
result:
ok 1 number(s): "595167333"
Test #24:
score: 0
Accepted
time: 13ms
memory: 19112kb
input:
97446 89750
output:
410205549
result:
ok 1 number(s): "410205549"
Test #25:
score: 0
Accepted
time: 18ms
memory: 19092kb
input:
186460 646474
output:
32638530
result:
ok 1 number(s): "32638530"
Test #26:
score: 0
Accepted
time: 46ms
memory: 19116kb
input:
508940 244684
output:
598321755
result:
ok 1 number(s): "598321755"
Test #27:
score: 0
Accepted
time: 52ms
memory: 19092kb
input:
583646 557758
output:
858695621
result:
ok 1 number(s): "858695621"
Test #28:
score: 0
Accepted
time: 84ms
memory: 19224kb
input:
969610 992608
output:
256683498
result:
ok 1 number(s): "256683498"
Test #29:
score: 0
Accepted
time: 87ms
memory: 19148kb
input:
995106 996434
output:
411791999
result:
ok 1 number(s): "411791999"
Test #30:
score: 0
Accepted
time: 81ms
memory: 19104kb
input:
999961 999872
output:
61222370
result:
ok 1 number(s): "61222370"
Test #31:
score: 0
Accepted
time: 84ms
memory: 19072kb
input:
999977 999908
output:
831096762
result:
ok 1 number(s): "831096762"
Test #32:
score: 0
Accepted
time: 82ms
memory: 19204kb
input:
999992 999998
output:
562977678
result:
ok 1 number(s): "562977678"
Test #33:
score: 0
Accepted
time: 12ms
memory: 19140kb
input:
1000000 2
output:
118436113
result:
ok 1 number(s): "118436113"
Test #34:
score: 0
Accepted
time: 11ms
memory: 19096kb
input:
2 1000000
output:
298823641
result:
ok 1 number(s): "298823641"