Submission #924689

#	Time	Username	Problem	Language	Result	Execution time	Memory
924689		NK_	Sure Bet (CEOI17_sure)	C++17	100 / 100	83 ms	3804 KiB

sure

// Success consists of going from failure to failure without loss of enthusiasm
#include <bits/stdc++.h>

using namespace std;

#define nl '\n'
#define pb push_back
#define sz(x) int(x.size())

using db = double;
using ll = long long;
template<class T> using V = vector<T>;
using vd = V<db>;

int main() {
	cin.tie(0)->sync_with_stdio(0);

	int N; cin >> N;

	vd A(N), B(N); for(int i = 0; i < N; i++) {
		cin >> A[i] >> B[i];
	}

	sort(rbegin(A), rend(A)); sort(rbegin(B), rend(B));

	for(int i = 1; i < N; i++) A[i] += A[i - 1];
	for(int i = 1; i < N; i++) B[i] += B[i - 1];

	// for(auto& x : A) cout << x << " ";
	// cout << endl;

	// for(auto& x : B) cout << x << " ";
	// cout << endl;

	db ans = 0;
	for(int x = 2; x <= 2 * N; x++) {
		// cout << x << " ===> " << endl;
		// take x odds	

		auto F = [&](int i) {
			if (i <= 0) return db(0);
			if (x - i <= 0) return db(0);
			return min(A[i - 1], B[x - 1 - i]) - x;
		};

		int lo = max(1, x - N), hi = min(x - 1, N);
		while(lo < hi) {
			int mid = (lo + hi + 1) / 2;
			if (A[mid - 1] < B[x - 1 - mid]) lo = mid;
			else hi = mid - 1;
		}

		ans = max(ans, F(lo - 1));
		ans = max(ans, F(lo));
		ans = max(ans, F(lo + 1));

		// maximize min_{1 <= i <= x}(A[i - 1] - x, B[x - i] - x)
	} 

	printf("%.4lf", ans);

	exit(0-0);
}

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