Submission #319732

#	Time	Username	Problem	Language	Result	Execution time	Memory
319732		BeanZ	Asceticism (JOI18_asceticism)	C++14	100 / 100	66 ms	1132 KiB

asceticism

// I_Love_LPL
#include <bits/stdc++.h>
using namespace std;
//#define task "A"
#define ll long long
#define endl '\n'
const int N = 1e5 + 10;
const int mod = 1e9 + 7;
ll fact[N];
ll binpow(ll u, ll p){
    if (p == 0) return 1;
    if (p == 1) return u;
    ll t = binpow(u, p / 2);
    if (p & 1) return t * t % mod * u % mod;
    else return t * t % mod;
}
ll nCk(ll n, ll k){
    return fact[n] * binpow(fact[n - k], mod - 2) % mod * binpow(fact[k], mod - 2) % mod;
}
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    if (fopen(".inp", "r")){
        freopen(".inp", "r", stdin);
        freopen(".out", "w", stdout);
    }
    ll n, m;
    cin >> n >> m;
    m--;
    fact[0] = 1;
    for (int i = 1; i <= (n + 1); i++) fact[i] = fact[i - 1] * i % mod;
    ll p = -1;
    ll ans = 0;
    for (int i = 0; i <= (m + 1); i++){
        p = p * -1;
        ans = (ans + p * nCk(n + 1, i) * binpow(m + 1 - i, n) + 1ll * mod * mod) % mod;
    }
    cout << ans;
}
/*
*/

Compilation message (stderr)

asceticism.cpp: In function 'int main()':
asceticism.cpp:24:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   24 |         freopen(".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~
asceticism.cpp:25:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   25 |         freopen(".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 20 / 20
• Subtask 3: 25 / 25
• Subtask 4: 51 / 51