Submission #3424790

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Source Code Expand

#include <bits/stdc++.h>

#define For(i, j, k) for (int i = j; i <= k; ++ i)
#define Forr(i, j, k) for (int i = j; i >= k; -- i)

using namespace std;

inline int read() {
	int x = 0, p = 1; char c = getchar();
	for (; !isdigit(c); c = getchar()) if (c == '-') p = -1;
	for (; isdigit(c); c = getchar()) x = (x << 1) + (x << 3) + (c ^ 48);
	return x * p;
}

inline void File() {
	freopen("D.in", "r", stdin);
	freopen("D.out", "w", stdout);
}

const int N = 2e5 + 10, mod = 1e9 + 7;
int fac[N], inv[N], n, m, c[N];
int isnot[N], prime[N], cnt, ps;

inline int qpow(int a, int b) {
	static int res;
	for (res = 1; b; b >>= 1, a = 1ll * a * a % mod)
		if (b & 1) res = 1ll * res * a % mod;
	return res;
}

inline void Init(int n) {
	isnot[1] = 1;
	For(i, 2, n) {
		if (!isnot[i]) prime[++ cnt] = i;
		For(j, 1, cnt) {
			if (1ll * i * prime[j] > n) break;
			isnot[i * prime[j]] = 1;
			if (i % prime[j] == 0) break;
		}
	}
	
	fac[0] = 1;
	For(i, 1, n) fac[i] = 1ll * i * fac[i - 1] % mod;
	inv[n] = qpow(fac[n], mod - 2);
	Forr(i, n - 1, 0) inv[i] = 1ll * (i + 1) * inv[i + 1] % mod;
}

inline int C(int n, int m) {
	return 1ll * fac[n] * inv[m] % mod * inv[n - m] % mod;
}

int main() {
	
	Init(N - 5);

	n = read(), m = read(), n = abs(n);

	for (int i = 1; prime[i] <= n && i <= cnt; ++ i) {
		for (; n % prime[i] == 0; ) n /= prime[i], ++ c[i]; ps = i;
	}

	int ans = 1;
	For(i, 1, ps) ans = 1ll * ans * C(c[i] + m - 1, m - 1) % mod;

	ans = 1ll * ans * qpow(2, m - 1) % mod;
	cout << ans << endl;

	return 0;
}

Submission Info

Judge Result