Cod sursa(job #1556690)

Utilizator howsiweiHow Si Wei howsiwei Data 25 decembrie 2015 18:00:23
Problema Cele mai apropiate puncte din plan Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.34 kb
#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <set>
#include <cmath>
#include <complex>
using namespace std;
typedef complex<double> Point;
const double oo = 2e9;

struct cmpx {
	bool operator () (const Point& a, const Point& b) const {
		return real(a) < real(b)
			|| real(a) == real(b) && imag(a) < imag(b);
	}
};

struct cmpy {
	bool operator () (const Point& a, const Point& b) const {
		return imag(a) < imag(b)
			|| imag(a) == imag(b) && real(a) < real(b);
	}
};

double sqdist(const Point& a, const Point& b) {
	return norm(b-a);
}

int main() {
	ios::sync_with_stdio(false);
	freopen("cmap.in", "r", stdin);
	freopen("cmap.out", "w", stdout);
	int n;
	cin >> n;
	vector<Point> P(n);
	for (int i = 0; i < n; i++) {
		double x, y;
		cin >> x >> y;
		P[i] = {x,y};
	}
	sort(P.begin(), P.end(), cmpx());

	set<Point,cmpy> sorty;
	double best = 4*oo;
	double sqbest = pow(best,2);
	int lox = 0;

	for (int i = 0; i < n; i++) {
		while (real(P[lox]) <= real(P[i])-best) {
			sorty.erase(P[lox]);
			lox++;
		}
		auto hi = sorty.lower_bound(Point(real(P[i]), imag(P[i])+best));
		for (auto it = sorty.upper_bound(Point(real(P[i]), imag(P[i])-best));
			it != hi; ++it) {
			if (sqbest > sqdist(P[i], *it)) {
				sqbest = sqdist(P[i], *it);
				best = sqrt(sqbest);
			}
		}
		sorty.insert(P[i]);
	}
	printf("%.6f\n", best);
}