Submission #57015

#	Time	Username	Problem	Language	Result	Execution time	Memory
57015		leejseo	Circle selection (APIO18_circle_selection)	C++98	19 / 100	1259 ms	69312 KiB

circle_selection

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

typedef pair<int, int> pii;

inline long long sq(long long x) { return x * x; }

typedef struct Circle{
	int x, y;
	int r;
	int i;
	Circle(int i_, int x_, int y_, int r_){ i = i_, x = x_, y = y_, r = r_; }
	bool meet(const Circle &c) const{
		return (sq((long long) (x - c.x)) + sq((long long) (y - c.y)) <= sq((long long) (r + c.r)));
	}
	bool operator < (const Circle &c) const{
		if (r != c.r) return r > c.r;
		return i < c.i;
	}
} Circle;

vector<Circle> L;
set<pii> S; //bst w/ x-coord & index

int ans[300000];
bool vis[300000];
int N;

int input(){
	scanf("%d", &N);
	int minr = 1<<30;
	int maxr = -1;
	bool ally0 = 1;
	int x, y, r;
	for (int i=0; i<N; i++){
		scanf("%d%d%d", &x, &y, &r);
		L.push_back(Circle(i, x, y, r));
		minr = min(minr, r);
		maxr = max(maxr, r);
		if (y != 0) ally0 = 0;
	}
	if (N <= 5000) return 1;
	if (ally0) return 2;
	if (minr == maxr) return 4;
	return 3; // we skip sub5/6 we assume sub3
}

void sub1(){
	sort(L.begin(), L.end());
	for (int i=0; i<N; i++){
		if (vis[i]) continue;
		int ind = L[i].i;
		ans[ind] = ind;
		vis[i] = 1;
		for (int j=0; j<N; j++){
			if (vis[j]) continue;
			if (L[i].meet(L[j])){
				ans[L[j].i] = ind;
				vis[j] = 1;
			}
		}
	}
}

void sub2(){
	sort(L.begin(), L.end());
	for (int i=0; i<N; i++){
		S.insert(pii(L[i].x - L[i].r, i));
		S.insert(pii(L[i].x + L[i].r, i));
	}
	set<pii>::iterator iter, temp;
	for (int i=0; i<N; i++){
		if (vis[i]) continue;
		int ind = L[i].i;
		ans[ind] = ind;
		vis[i] = 1;
		iter = S.lower_bound(make_pair(L[i].x-L[i].r, 0));
		while ((iter != S.end())&&(!S.empty())){
			temp = iter;
			temp++;
			if ((*iter).first <= L[i].x + L[i].r){
				int j = (*iter).second;
				if (!vis[j]){
					ans[L[j].i] = ind;
					vis[j] = 1;
				}
			}
			S.erase(iter);
			if ((temp == S.end()) || ((*temp).first > L[i].x + L[i].r)) break;
			iter = temp;
		}
	}
}

int main(void){
	int st = input();
	if (st == 1){
		sub1();
		for (int i=0; i<N; i++){
			printf("%d ", ans[i]+1);
		}
		printf("\n");
	}
	else if (st == 2){
		sub2();
		for (int i=0; i<N; i++) printf("%d ", ans[i] + 1);
		printf("\n");
	}
	else{
		printf("-1");
	}
}

Compilation message (stderr)

circle_selection.cpp: In function 'int input()':
circle_selection.cpp:30:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &N);
  ~~~~~^~~~~~~~~~
circle_selection.cpp:36:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d%d", &x, &y, &r);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~

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