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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
#106727#6417. Classical Summation ProblemhongrockWA 2ms3544kbC++171.6kb2023-05-18 22:02:172023-05-18 22:02:19

Judging History

你现在查看的是最新测评结果

  • [2023-08-10 23:21:45]
  • System Update: QOJ starts to keep a history of the judgings of all the submissions.
  • [2023-05-18 22:02:19]
  • 评测
  • 测评结果:WA
  • 用时:2ms
  • 内存:3544kb
  • [2023-05-18 22:02:17]
  • 提交

answer

#include<bits/stdc++.h>
using namespace std;

#define rep(i, a, n) for(int i=(a); i<(n); ++i)
#define per(i, a, n) for(int i=(a); i>(n); --i)
#define pb emplace_back
#define mp make_pair
#define clr(a, b) memset(a, b, sizeof(a))
#define all(x) (x).begin(),(x).end()
#define lowbit(x) (x & -x)
#define fi first
#define se second
#define lson o<<1
#define rson o<<1|1
#define gmid l[o]+r[o]>>1
 
using ll = long long;
using ull = unsigned long long;
using pii = pair<int,int>;
using pll = pair<ll, ll>;
using ui = unsigned int;
 
constexpr int mod = 998244353;
constexpr int inf = 0x3f3f3f3f;
constexpr double EPS = 1e-8;
const double PI = acos(-1.0);

constexpr int N = 1e6 + 10;

ll pow_mod(ll x, int p){
  ll s = 1;
  while(p){
    if(p & 1) s = s * x % mod;
    x = x * x % mod;
    p >>= 1;
  }
  return s;
}

int n, k;
ll fac[N], rev[N];

ll C(int n, int m){
  return fac[n] * rev[m] % mod * rev[n - m] % mod;
}

void _main(){
  cin >> n >> k;
  ll e = 0;
  e = (1 + n) * pow_mod(2, mod - 2) % mod;
  if(k % 2 == 0){
    fac[0] = 1;
    rep(i, 1, n + 1)  fac[i] = fac[i-1] * i % mod;
    rev[n] = pow_mod(fac[n], mod - 2);
    per(i, n, 0)  rev[i-1] = rev[i] * i % mod;
    ll d = 0;
    rep(i, 1, n){
      d = d + pow_mod(i, k / 2) * pow_mod(n - i, k / 2) % mod;
    }
    d = d % mod * C(k, k / 2) % mod * pow_mod(pow_mod(n, mod - 2), k) % mod;
    d = d * pow_mod(2, mod - 2) % mod;
    e = (e + mod - d) % mod;
  }

  cout << e * pow_mod(n, k) % mod << '\n';
}

int main(){
  ios::sync_with_stdio(0);
  cin.tie(0); cout.tie(0);
  _main();
  return 0;
}

详细

Test #1:

score: 100
Accepted
time: 2ms
memory: 3352kb

input:

3 2

output:

14

result:

ok 1 number(s): "14"

Test #2:

score: 0
Accepted
time: 0ms
memory: 3384kb

input:

5 3

output:

375

result:

ok 1 number(s): "375"

Test #3:

score: 0
Accepted
time: 2ms
memory: 3308kb

input:

2 2

output:

5

result:

ok 1 number(s): "5"

Test #4:

score: 0
Accepted
time: 0ms
memory: 3384kb

input:

10 9

output:

508778235

result:

ok 1 number(s): "508778235"

Test #5:

score: 0
Accepted
time: 2ms
memory: 3472kb

input:

69 3

output:

11497815

result:

ok 1 number(s): "11497815"

Test #6:

score: 0
Accepted
time: 0ms
memory: 3468kb

input:

994 515

output:

33689623

result:

ok 1 number(s): "33689623"

Test #7:

score: -100
Wrong Answer
time: 1ms
memory: 3544kb

input:

4476 6182

output:

505051055

result:

wrong answer 1st numbers differ - expected: '114894183', found: '505051055'