小白月初赛-杨辉三角形(数论)

Posted 2021-08-15 zjj0624

题意

思路

代码

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll mod = 99824353;
ll qmi(ll a,ll b){
    ll ans = 1;
    while (b)
    {
        if (b & 1) ans = ans * a % mod;
        b >>= 1;
        a = a * a % mod;
    }
    return ans;
}

int main()
{
    ll n; cin >> n;
    n --;
    if (n == 0) cout << 0 << endl;
    else if (n == 1) cout << 1 << endl;
    else cout << (n % mod * qmi(1ll* 2, n - 1) % mod + n % mod * (n - 1) % mod * qmi(1ll * 2, n - 2) % mod) % mod << endl;
    return 0;
}