Submission #165213

#	Time	Username	Problem	Language	Result	Execution time	Memory
165213		coloredrabbit	Ω (kriii4_P3)	C++17	100 / 100	7 ms	504 KiB

P3

#include <iostream>
using ll = long long;
const ll MOD = 1e9 + 7;
ll _pow(ll a, int n) {
	if (n <= 1) return n % 2 ? a : 1;
	ll h = _pow(a, n >> 1);
	return (((h * h) % MOD) * (n % 2 ? a : 1)) % MOD;
}
ll rev(ll x) { return _pow(x % MOD, MOD - 2); }
int main() {
	int P, Q, N, K;
	ll v, ans = 0, A, B, g, X;
	scanf("%d%d%d%d", &P, &Q, &N, &K);
	if (K == 0) puts("0");
	else if (K == N) puts("1");
	else if (Q == 0) puts("1");	
	else if (Q == P) puts("0");
	else {
		if (2 * Q == P)
			ans = (K * rev(N)) % MOD;
		else {
			v = (Q * rev(P - Q)) % MOD;
			ans = (((1 - _pow(v, K) + MOD) % MOD) * (rev(1 - _pow(v, N) + MOD) % MOD)) % MOD;
		}
		std::cout << ans;
	}

	return 0;
}

Compilation message (stderr)

P3.cpp: In function 'int main()':
P3.cpp:12:17: warning: unused variable 'A' [-Wunused-variable]
  ll v, ans = 0, A, B, g, X;
                 ^
P3.cpp:12:20: warning: unused variable 'B' [-Wunused-variable]
  ll v, ans = 0, A, B, g, X;
                    ^
P3.cpp:12:23: warning: unused variable 'g' [-Wunused-variable]
  ll v, ans = 0, A, B, g, X;
                       ^
P3.cpp:12:26: warning: unused variable 'X' [-Wunused-variable]
  ll v, ans = 0, A, B, g, X;
                          ^
P3.cpp:13:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d%d%d", &P, &Q, &N, &K);
  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 100 / 100