Submission #132835

#	Time	Username	Problem	Language	Result	Execution time	Memory
132835		duality	Asceticism (JOI18_asceticism)	C++11	100 / 100	26 ms	504 KiB

asceticism

#include <bits/stdc++.h>
using namespace std;
#define mp make_pair
#define pb push_back
typedef long long int LLI;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pii> vpii;
#define MOD 1000000007

LLI modPow(LLI b,int e) {
    LLI r = 1;
    while (e > 0) {
        if (e & 1) r *= b,r %= MOD;
        e >>= 1;
        b *= b,b %= MOD;
    }
    return r;
}
int main() {
    int N,K;
    cin >> N >> K;

    int i;
    LLI ans = 0,c = 1;
    for (i = 0; i < K; i++) {
        if (!(i & 1)) ans += modPow(K-i,N)*c,ans %= MOD;
        else ans -= modPow(K-i,N)*c,ans %= MOD;
        c *= (N+1-i),c %= MOD;
        c *= modPow(i+1,MOD-2),c %= MOD;
    }
    if (ans < 0) ans += MOD;
    cout << ans << endl;

    return 0;
}

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