Submission #19834

# Submission time Handle Problem Language Result Execution time Memory
19834 2016-02-25T06:07:05 Z xdoju 팔찌 (kriii4_V) C++14
6 / 100
1000 ms 18400 KB
#include <cstdio>
#include <cmath>
#include <vector>
using namespace std;

const long long MOD = 1000000007ll;

long long modpow(long long r, long long n) {
	long long ret = 1;
	while (n > 0) {
		if (n % 2 > 0) {
			ret = (ret * r) % MOD;
		}
		r = (r * r) % MOD;
		n /= 2;
	}
	return ret;
}

long long modinv(long long n) {
	return modpow(n, MOD - 2);
}

long long modprod(long long a, long long b) {
	a = a % MOD;
	b = b % MOD;
	return (a * b) % MOD;
}

long long modprod(long long a, long long b, long long c) {
	c = c % MOD;
	return (modprod(a, b) * c) % MOD;
}

long long moddiv(long long a, long long b) {
	return (a * modinv(b)) % MOD;
}

long long gcd(long long a, long long b) {
	if (a < b) {
		return gcd(b, a);
	}
	return (b == 0) ? a : gcd(b, a % b);
}

const int N = 1000000;
long long lp[N + 1];
long long phi[N + 1];
vector<long long> pr;

void sieve() {
	phi[1] = 1;
	for (int i = 2; i <= N; ++i) {
		if (lp[i] == 0) {
			lp[i] = i;
			phi[i] = i - 1;
			pr.push_back(i);
		}
		else {
			if (lp[i] == lp[i / lp[i]]) {
				phi[i] = phi[i / lp[i]] * lp[i];
			}
			else {
				phi[i] = phi[i / lp[i]] * (lp[i] - 1);
			}
		}
		for (int j = 0; j < (int)pr.size() && pr[j] <= lp[i] && i * pr[j] <= N; ++j) {
			lp[i * pr[j]] = pr[j];
		}
	}
}

void proc() {
	sieve();

	long long n, k;
	scanf("%lld %lld", &n, &k);

	long long ans = 1;
	for (long long i = 1; i <= n; ++i) {
		long long t = 0;

		long long lmt = (long long)(sqrt(i) + 0.00001);
		for (long long p = 1; p <= lmt; ++p) {
			if (i % p != 0) {
				continue;
			}

			t = (t + modprod(modpow(k, i / p), phi[p])) % MOD;
			if (p * p < i) {
				t = (t + modprod(modpow(k, p), phi[i / p])) % MOD;
			}
		}
		t = moddiv(t, i);


		long long u = 0;
		if (i % 2 == 0) {
			u = moddiv(t, 2);
			long long v = modprod(k + 1, modpow(k, i / 2));
			v = moddiv(v, 4);
			u = (u + v) % MOD;
		}
		else {
			u = moddiv(t, 2);
			long long v = modpow(k, (i + 1) / 2);
			v = moddiv(v, 2);
			u = (u + v) % MOD;
		}

		ans = (ans + u) % MOD;
	}
	printf("%lld", ans);
}

int main() {
	//freopen("input.txt", "r", stdin);
	proc();
	return 0;
}
# Verdict Execution time Memory Grader output
1 Correct 21 ms 18400 KB Output is correct
2 Correct 32 ms 18400 KB Output is correct
3 Correct 30 ms 18400 KB Output is correct
4 Correct 27 ms 18400 KB Output is correct
5 Correct 33 ms 18400 KB Output is correct
6 Correct 29 ms 18400 KB Output is correct
7 Correct 32 ms 18400 KB Output is correct
8 Correct 30 ms 18400 KB Output is correct
9 Correct 32 ms 18400 KB Output is correct
10 Correct 29 ms 18400 KB Output is correct
11 Correct 31 ms 18400 KB Output is correct
12 Correct 24 ms 18400 KB Output is correct
13 Correct 33 ms 18400 KB Output is correct
14 Correct 28 ms 18400 KB Output is correct
15 Correct 32 ms 18400 KB Output is correct
16 Correct 29 ms 18400 KB Output is correct
17 Correct 32 ms 18400 KB Output is correct
18 Correct 28 ms 18400 KB Output is correct
19 Correct 24 ms 18400 KB Output is correct
20 Correct 29 ms 18400 KB Output is correct
# Verdict Execution time Memory Grader output
1 Correct 25 ms 18400 KB Output is correct
2 Correct 33 ms 18400 KB Output is correct
3 Correct 34 ms 18400 KB Output is correct
4 Correct 244 ms 18400 KB Output is correct
5 Execution timed out 1000 ms 18400 KB Program timed out
6 Halted 0 ms 0 KB -