Submission #47476

#	Time	Username	Problem	Language	Result	Execution time	Memory
47476		Talant	Asceticism (JOI18_asceticism)	C++17	100 / 100	51 ms	1488 KiB

asceticism

#include <bits/stdc++.h>

#define mk make_pair
#define sc second
#define fr first
#define pb emplace_back
#define all(s) s.begin(), s.end()
#define sz(s) ( (int)s.size() )
#define int long long

using namespace std;

const int inf = (int)1e9 + 7;
const int N = (int)1e5 + 7;

int n,m;
int f[N];
int ans;

int binpow (int a,int b) {
      int res = 1;
      while (b) {
            if (b & 1)
                  res *= a;
            a *= a;
            b >>= 1;
            a %= inf;
            res %= inf;
      }
      return (res % inf);
}
int cnk(int n,int k) {
      return ((f[n] * binpow(f[n - k],inf - 2)) % inf * binpow(f[k],inf - 2) % inf);
}
int fun(int k) {
      return ((cnk(n + 1,k) * binpow(m - k,n)) % inf);
}
main() {
      f[0] = 1;
      for (int i = 1; i <= N - 5; i ++)
            f[i] = (f[i - 1] * i) % inf;

      cin >> n >> m;

      for (int i = 0; i <= m; i ++) {
            if (i & 1)
                  ans = (ans + inf - fun(i)) % inf;
            else
                  ans = (ans + fun(i)) % inf;
      }
      cout << ans << endl;
}

Compilation message (stderr)

asceticism.cpp:38:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main() {
      ^

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