제출 #19758

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
19758		tonyjjw	괄호 (kriii4_R)	C++14	100 / 100	765 ms	17348 KiB

R

#include <algorithm>
#include <assert.h>
#include <complex>
#include <ctype.h>
#include <functional>
#include <iostream>
#include <limits.h>
#include <locale.h>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <vector>
#include <unordered_set>
#include <unordered_map>

#pragma warning(disable:4996)
using namespace std;

#define mp make_pair
typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef long double ldb;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;
typedef pair <ll, int> pli;
typedef pair <ldb, ldb> pdd;

int IT_MAX = 131072;
const ll MOD = 1000000007;
const int INF = 1034567891;
const ll LL_INF = 2234567890123456789ll;
const db PI = 3.141592653589793238;
const ldb ERR = 1E-10;

ll mul_inv(ll a, ll b)
{
	ll b0 = b, t, q;
	ll x0 = 0, x1 = 1;
	if (b == 1) return 1;
	while (a > 1) {
		q = a / b;
		t = b, b = a % b, a = t;
		t = x0, x0 = x1 - q * x0, x1 = t;
	}
	if (x1 < 0) x1 += b0;
	return x1;
}

ll F[1000050];
ll powK[1000050];
ll C(int i, int j) {
	ll rv = F[i];
	rv = (rv * mul_inv(F[j], MOD)) % MOD;
	rv = (rv * mul_inv(F[i - j], MOD)) % MOD;
	return rv;
}

int main() {
	int N, K, i;
	scanf("%d %d", &N, &K);
	
	F[0] = 1, powK[0] = 1;
	for (i = 1; i <= N; i++) F[i] = (F[i - 1] * i) % MOD;
	for (i = 1; i <= N; i++) powK[i] = (powK[i - 1] * K) % MOD;

	ll ans = powK[N];
	for (i = 1; i <= N / 2; i++) {
		ll t = (C(N, i) - C(N, i - 1) + MOD) % MOD;
		ans = (ans + t * powK[N - i]) % MOD;
	}
	printf("%lld\n", ans);
	return 0;
}

• Subtask 1: 8 / 8
• Subtask 2: 92 / 92