Submission #453749

#	Time	Username	Problem	Language	Result	Execution time	Memory
453749		arminatarod	Circle selection (APIO18_circle_selection)	C++17	15 / 100	2473 ms	159236 KiB

circle_selection

#include <bits/stdc++.h>
 
using namespace std;
 
constexpr int MAXN = 300005;
 
constexpr int MAXINT = 1073741823;

vector<int> all_numbers;
 
vector<int> neighbors[MAXN];
 
struct circles {
	long long int x, y, radius;
} circle[MAXN];
 
int sorted[MAXN], answer[MAXN];
 
bitset<MAXN> deleted;
 
bool comparison(int x, int y) {
	return (circle[x].radius == circle[y].radius? x < y : circle[x].radius > circle[y].radius);
}

map<int, vector<pair<int, int>>> to_add, to_delete;

set<pair<int, int>> s;

set<pair<int, int>>::iterator it;

bool check(circles u, circles v) {
	long long int distance_2 = (u.x - v.x) * (u.x - v.x) + (u.y - v.y) * (u.y - v.y);
	long long int radius_2 = (u.radius + v.radius) * (u.radius + v.radius);
	return (radius_2 >= distance_2);
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	long long int n, distance_2, radius_2;
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> circle[i].x >> circle[i].y >> circle[i].radius;
		all_numbers.push_back(circle[i].y - circle[i].radius);
		all_numbers.push_back(circle[i].y + circle[i].radius);
		to_add[circle[i].y - circle[i].radius].emplace_back(circle[i].x, i);
		to_delete[circle[i].y + circle[i].radius].emplace_back(circle[i].x, i);
		sorted[i] = i;
	}
	sort(sorted, sorted + n, comparison);
	sort(all_numbers.begin(), all_numbers.end());
	all_numbers.resize(distance(all_numbers.begin(), unique(all_numbers.begin(), all_numbers.end())));
	for (int i : all_numbers) {
		for (pair<int, int> j : to_add[i]) {
			s.insert(j);
			it = s.lower_bound(j);
			if (it != s.begin()) {
				it--;
				if (check(circle[it->second], circle[j.second])) {
					neighbors[it->second].push_back(j.second);
					neighbors[j.second].push_back(it->second);
				}
				it++;
			}
			if (*it != *s.rbegin()) {
				it++;
				if (check(circle[it->second], circle[j.second])) {
					neighbors[it->second].push_back(j.second);
					neighbors[j.second].push_back(it->second);
				}
				it--;
			}
		}
		for (pair<int, int> j : to_delete[i]) {
			it = s.lower_bound(j);
			if (it != s.begin()) {
				it--;
				if (check(circle[it->second], circle[j.second])) {
					neighbors[it->second].push_back(j.second);
					neighbors[j.second].push_back(it->second);
				}
				it++;
			}
			if (*it != *s.rbegin()) {
				it++;
				if (check(circle[it->second], circle[j.second])) {
					neighbors[it->second].push_back(j.second);
					neighbors[j.second].push_back(it->second);
				}
				it--;
			}
			s.erase(j);
		}
	}
	for (int i = 0; i < n; i++)
		if (!deleted[sorted[i]]) {
			answer[sorted[i]] = sorted[i];
			deleted[sorted[i]] = true;
			for (int j : neighbors[sorted[i]]) {
				if (deleted[j])
					continue;
				answer[j] = sorted[i];
				deleted[j] = true;
			}
		}
	for (int i = 0; i < n; i++)
		cout << answer[i] + 1 << ' ';
	return 0;
}

Compilation message (stderr)

circle_selection.cpp: In function 'int main()':
circle_selection.cpp:40:19: warning: unused variable 'distance_2' [-Wunused-variable]
   40 |  long long int n, distance_2, radius_2;
      |                   ^~~~~~~~~~
circle_selection.cpp:40:31: warning: unused variable 'radius_2' [-Wunused-variable]
   40 |  long long int n, distance_2, radius_2;
      |                               ^~~~~~~~

• Subtask 1: 0 / 7
• Subtask 2: 0 / 12
• Subtask 3: 15 / 15
• Subtask 4: 0 / 23
• Subtask 5: 0 / 30
• Subtask 6: 0 / 13