Submission #1116648

#	Time	Username	Problem	Language	Result	Execution time	Memory
1116648		shidou26	Sure Bet (CEOI17_sure)	C++14	100 / 100	443 ms	5316 KiB

sure

#include <bits/stdc++.h>
using namespace std;

#define endl '\n'
#define all(v) v.begin(), v.end()
#define dbg(v) "[" #v " = " << (v) << "]"

template<typename T> bool maximize(T &a, T b) {
	if(a < b) {
		a = b;
		return true;
	}else return false;
}
template<typename T> bool minimize(T &a, T b) {
	if(a > b) {
		a = b;
		return true;
	}else return false;
}

typedef long long ll;
typedef pair<int, int> ii;
typedef pair<ll, int> li;

const int N = 1e5 + 3;

int n;
double a[N], b[N];

namespace subtask1 {
	double best = 0;

	void backtrack(int p, double totalA, double totalB, int counter) {
		if(p > n) {
			maximize(best, min(totalA - (double)counter, totalB - (double)counter));
			return;
		}
		backtrack(p + 1, totalA, totalB, counter);
		backtrack(p + 1, totalA + a[p], totalB, counter + 1);
		backtrack(p + 1, totalA, totalB + b[p], counter + 1);
		backtrack(p + 1, totalA + a[p], totalB + b[p], counter + 2);
	}

	void solve() {
		backtrack(1, 0, 0, 0);
		cout << fixed << setprecision(4) << best << endl;
	}
};

namespace subtask3 {
	double prefA[N], prefB[N];

	bool check(double x, int p) {
		int limitA = lower_bound(prefA + 1, prefA + 1 + n, x) - prefA;
		int limitB = lower_bound(prefB + 1, prefB + 1 + n, x) - prefB;
		if(limitA == n + 1 || limitB == n + 1)
			return false;
		else return (limitA + limitB <= p);
	}

	void solve() {
		sort(a + 1, a + 1 + n, greater<double>());
		sort(b + 1, b + 1 + n, greater<double>());

		for(int i = 1; i <= n; i++) prefA[i] = prefA[i - 1] + a[i];
		for(int i = 1; i <= n; i++) prefB[i] = prefB[i - 1] + b[i];

		double best = 0;
		for(int p = 1; p <= 2 * n; p++) {
			double l = 0, r = 1e9 + 3;
			for(int rep = 1; rep <= 50; rep++) {
				double mid = (l + r) / 2.0;
				if(check(mid, p)) {
					l = mid;
				}else r = mid;
			}
			maximize(best, l - p);
		}
		cout << fixed << setprecision(4) << best << endl;
	}
}

void process() {
	if(n <= 10) {
		subtask1::solve();
		return;
	}	

	subtask3::solve();
}


void input() {
	cin >> n;

	for(int i = 1; i <= n; i++) {
		cin >> a[i] >> b[i];
	}	
}

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);

	#define task "DateALive"
	if(fopen(task".INP", "r")) {
		freopen(task".INP", "r", stdin);
		freopen(task".OUT", "w", stdout);
	}

	input();
	process();

	return 0;
}

Compilation message (stderr)

sure.cpp: In function 'int main()':
sure.cpp:107:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  107 |   freopen(task".INP", "r", stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
sure.cpp:108:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  108 |   freopen(task".OUT", "w", stdout);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 20 / 20
• Subtask 2: 40 / 40
• Subtask 3: 40 / 40