Submission #1303282

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Source Code Expand

#include <iostream>
#include <vector>
#include <algorithm>
#include <iomanip>

using namespace std;
using ll = long long;

ll combination(ll n, ll k) {
    ll r = 1;
    for (ll d = 1; d <= k; ++d) {
        r *= n--;
        r /= d;
    }
    return r;
}

int main(){
	// input
	// A <= x <= B
	int N, A, B;
	cin >> N >> A >> B;

	vector<ll> v(N);
	for (int i = 0; i < N; ++i) {
		cin >> v[i];
	}

	// sort
	sort(v.begin(), v.end(), greater<ll>());

	// calculate max average
	long double average = 0;
	for (int i; i < A; ++i) {
		average += v[i];
	}
	average /= A;
	cout << fixed << average << endl;

	// calculate combination
	ll n = v[A - 1];
	int min_i = 0;
	int max_i = N-1;
	
	while(v[min_i] != n){
		min_i++;
	}
	while(v[max_i] != n){
		max_i--;
	}
	int w = max_i - min_i + 1;
	
	ll comb = 0;
	for (int k = A - min_i; k <= B - min_i; ++k) {
		if (v[min_i + k - 1] != n) {
			break;
		}
		comb += combination(w, k);
		if (min_i != 0) {
			break;
		}
	}


	cout << comb << endl;
}

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