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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
#406247#6736. Alice and BobguggTL 0ms0kbC++202.7kb2024-05-06 23:15:562024-05-06 23:15:58

Judging History

你现在查看的是最新测评结果

  • [2024-05-06 23:15:58]
  • 评测
  • 测评结果:TL
  • 用时:0ms
  • 内存:0kb
  • [2024-05-06 23:15:56]
  • 提交

answer

#include <iostream>
#include <algorithm>
#include <cstring>
#include <vector>
#include <queue>
#include <unordered_map>
#include <unordered_set>
#include <map>
#include <set>
#include <cmath>
#include <bitset>
#include <cassert>
#include <numeric>

using namespace std;
typedef long long ll;

constexpr int P = 998244353;
// assume -P <= x < 2P
ll norm(ll x) {
    if (x < 0) {
        x += P;
    }
    if (x >= P) {
        x -= P;
    }
    return x;
}
template<class T>
T power(T a, int b) {
    T res = 1;
    for (; b; b /= 2, a *= a) {
        if (b % 2) {
            res *= a;
        }
    }
    return res;
}
struct Z {
    ll x;
    Z(ll x = 0) : x(norm(x% P)) {}
    ll val() const {
        return x;
    }
    Z operator-() const {
        return Z(norm(P - x));
    }
    Z inv() const {
        assert(x != 0);
        return power(*this, P - 2);
    }
    Z& operator*=(const Z& rhs) {
        x = x * rhs.x % P;
        return *this;
    }
    Z& operator+=(const Z& rhs) {
        x = norm(x + rhs.x);
        return *this;
    }
    Z& operator-=(const Z& rhs) {
        x = norm(x - rhs.x);
        return *this;
    }
    Z& operator/=(const Z& rhs) {
        return *this *= rhs.inv();
    }
    friend Z operator*(const Z& lhs, const Z& rhs) {
        Z res = lhs;
        res *= rhs;
        return res;
    }
    friend Z operator+(const Z& lhs, const Z& rhs) {
        Z res = lhs;
        res += rhs;
        return res;
    }
    friend Z operator-(const Z& lhs, const Z& rhs) {
        Z res = lhs;
        res -= rhs;
        return res;
    }
    friend Z operator/(const Z& lhs, const Z& rhs) {
        Z res = lhs;
        res /= rhs;
        return res;
    }
    friend std::istream& operator>>(std::istream& is, Z& a) {
        ll v;
        is >> v;
        a = Z(v);
        return is;
    }
    friend std::ostream& operator<<(std::ostream& os, const Z& a) {
        return os << a.val();
    }
};

const int N = 10000010;

Z fact[N], infact[N];

void init()
{
    fact[0] = infact[0] = 1;
    for (int i = 1; i < N; i ++ )
    {
        fact[i] = fact[i - 1] * i;
        infact[i] = infact[i - 1] / i;
    }
}
 
Z A(int a, int b)
{
    return fact[a] * infact[a - b];
}

void solve()
{
    int n;
    cin >> n;
    Z ans = 0;
    for (int i = 1; i <= n; i ++)
    {
        if (n - i < i - 1) break;
        ans += A(n - i, i - 1) * fact[n - i];
    }
    cout << ans << '\n';
}

int main()
{
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);

    init();
    int tt = 1;
    // cin >> tt;
    while (tt --)
    {
        solve();
    }
    return 0;
}

详细

Test #1:

score: 0
Time Limit Exceeded

input:

1

output:


result: