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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
#350637#6736. Alice and BobAlbert711RE 0ms0kbC++201.6kb2024-03-10 22:24:482024-03-10 22:24:48

Judging History

你现在查看的是最新测评结果

  • [2024-03-10 22:24:48]
  • 评测
  • 测评结果:RE
  • 用时:0ms
  • 内存:0kb
  • [2024-03-10 22:24:48]
  • 提交

answer

#include<bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef double db;
const int N = 1e7 + 5;
const int mod = 998244353;
//#define int long long

using i64 = int64_t;
std::bitset<N> bt[N];

i64 fpow(i64 x, i64 r) {
    i64 result = 1;
    while (r) {
        if (r & 1)result = result * x % mod;
        r >>= 1;
        x = x * x % mod;
    }
    return result;
}

namespace binom {
    i64 fac[N], ifac[N];
    int __ = [] {
        fac[0] = 1;
        for (int i = 1; i <= N - 5; i++)
            fac[i] = fac[i - 1] * i % mod;
        ifac[N - 5] = fpow(fac[N - 5], mod - 2);
        for (int i = N - 5; i; i--)
            ifac[i - 1] = ifac[i] * i % mod;
        return 0;
    }();

    inline i64 C(int n, int m) {
        if (n < m || m < 0)return 0;
        return fac[n] * ifac[m] % mod * ifac[n - m] % mod;
    }

    inline i64 A(int n, int m) {
        if (n < m || m < 0)return 0;
        return fac[n] * ifac[n - m] % mod;
    }
}
using namespace binom;

void solve() {
    ll n;
    cin >> n;
    if(n==1) {
        cout<<1<<'\n';return;
    }
    ll ans = 0;
    ll tmp = 1;
    for (int i = 1; i <= n - 1; i++) tmp = tmp * i % mod;
    ll tt = tmp;
    for (int i = 1; i <= n; i++) {
        if (i - 1 > n - i) break;
        ans = ans + A(n - i, i - 1) * tt % mod;
        ans %= mod;
        tt = tt * fpow(n - i, mod - 2) % mod;
    }
    cout << ans << '\n';
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
//    cout << fixed << setprecision(1);
    int T = 1;
//    cin >> T;
    while (T--) solve();
    return 0;
}




詳細信息

Test #1:

score: 0
Runtime Error

input:

1

output:


result: