Submission #49614

#	Time	Username	Problem	Language	Result	Execution time	Memory
49614		Diuven	Circle selection (APIO18_circle_selection)	C++11	49 / 100	3051 ms	66736 KiB

circle_selection

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
const int MX=300010, inf=2e9;

struct CIRCLE {
	int x, y, r, idx, kill;
} C[MX];

inline ll sq(ll x){ return x*x; }
inline ll dist(int a, int b){
	return sq(C[a].x-C[b].x)+sq(C[a].y-C[b].y);
}
inline bool hit(int a, int b){
	return dist(a,b)<=sq(C[a].r+C[b].r);
}

int n;

void input(){
	cin>>n;
	for(int i=1; i<=n; i++){
		int x, y, r;
		cin>>x>>y>>r;
		C[i]={x,y,r,i,0};
	}
}

vector<vector<vi>> G;
ll t=1<<30;
// [-t, 0), [0, t)

inline int sect(int idx, int x0, int y0){
	// 1 3
	// 0 2
	int x=C[idx].x, y=C[idx].y;
	if(x<x0)
		if(y<y0) return 0;
		else return 1;
	else
		if(y<y0) return 2;
		else return 3;
}

inline int range(ll x){
	if(x>0) return x/t;
	return -((-x+t-1)/t);
}
inline int xrange(const vi &cell){
	return range(C[cell.front()].x);
}
inline int yrange(const vi &cell){
	return range(C[cell.front()].y);
}
inline int xrange(const vector<vi> &X){
	return xrange(X.front());
}


void init_grid(){
	vi V[4];
	for(int i=1; i<=n; i++){
		V[sect(i,0,0)].push_back(i);
	}
	vector<vi> X[2];
	for(int k=0; k<4; k++)
		if(!V[k].empty())
			X[k/2].push_back(V[k]);

	if(!X[0].empty()) G.push_back(X[0]);
	if(!X[1].empty()) G.push_back(X[1]);
}

void resize_grid(){
	vector<vector<vi>> tmp;
	for(auto &X:G){
		vector<vi> newX[2];
		for(vi &cell:X){
			vi V[4];
			int x=xrange(cell)*t + t/2;
			int y=yrange(cell)*t + t/2;
			for(int idx:cell){
				if(C[idx].kill!=0) continue;
				V[sect(idx,x,y)].push_back(idx);
			}
			for(int k=0; k<4; k++)
				if(!V[k].empty())
					newX[k/2].push_back(V[k]);
		}
		if(!newX[0].empty()) tmp.push_back(newX[0]);
		if(!newX[1].empty()) tmp.push_back(newX[1]);
	}
	// slow!!!
	G=tmp;
	t/=2;
}
void process(vi &cell, int killer){
	vi tmp;
	for(int killed:cell){
		if(C[killed].kill==0 && hit(killed, killer))
			C[killed].kill=killer;
		if(C[killed].kill==0) tmp.push_back(killed);
	}
	cell=tmp;
}

void kill(int idx){
	while(C[idx].r*2<t){
		resize_grid();
	}
	int x=C[idx].x, y=C[idx].y;
	ll lx=range(x)-2, hx=range(x)+3;
	ll ly=range(y)-2, hy=range(y)+3;
	
	int n1=G.size();
	int s1=0, e1=n1-1;
	while(s1<e1){
		int m1=(s1+e1)/2;
		if(xrange(G[m1])<lx) s1=m1+1;
		else e1=m1;
	}
	int pos=s1;
	while(pos<min(n1,s1+5) && lx<=xrange(G[pos]) && xrange(G[pos])<=hx){
		vector<vi> &X=G[pos];
		int n2=X.size();
		int s2=0, e2=n2-1;
		while(s2<e2){
			int m2=(s2+e2)/2;
			if(yrange(X[m2])<ly) s2=m2+1;
			else e2=m2;
		}
		while(s2<n2 && ly<=yrange(X[s2]) && yrange(X[s2])<=hy){
			process(X[s2], idx);
			s2++;
		}
		pos++;
	}
}

void solve(){
	CIRCLE D[MX];
	for(int i=1; i<=n; i++) D[i]=C[i];
	sort(D+1, D+n+1, [](CIRCLE &a, CIRCLE &b){
		if(a.r==b.r) return a.idx<b.idx;
		return a.r>b.r;
	});
	for(int i=1; i<=n; i++){
		int idx=D[i].idx;
		if(C[idx].kill!=0) continue;
		kill(idx);
	}
}

int main(){
	ios::sync_with_stdio(0); cin.tie(0);
	input();
	init_grid();
	solve();
	
	for(int i=1; i<=n; i++) cout<<C[i].kill<<' ';
	return 0;
}

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