Submission #204940

#	Time	Username	Problem	Language	Result	Execution time	Memory
204940		oolimry	Circle selection (APIO18_circle_selection)	C++14	49 / 100	3096 ms	352516 KiB

circle_selection

#include <bits/stdc++.h>
 
using namespace std; 
int n; 
 
struct Circle{
	long long x, y, r, id;
} sorted[300005], arr[300005];;
 
inline bool intersect(Circle a, Circle b){
	return (a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y) <= (a.r + b.r) * (a.r + b.r);
}
 
inline long long ii(long long a, long long b){
	return a * (1LL << 32LL) + b;
}
long long ans[300005];
 
 struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        // http://xorshift.di.unimi.it/splitmix64.c
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }
    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};

unordered_map<long long, vector<int>, custom_hash> GRID;
long long gridSize = 1LL << 61LL;
 
inline void buildGrid(long long newGridSize){
	gridSize = newGridSize;
	GRID.clear();
	
	for(int i = 0;i < n;i++){
		if(ans[i] == -1){
			long long xSquare = arr[i].x / gridSize;
			long long ySquare = arr[i].y / gridSize;
			GRID[ii(xSquare,ySquare)].push_back(i);
		}
	}
}
 
bool comp(Circle a, Circle b){
	if(a.r == b.r) return a.id < b.id;
	else return a.r > b.r;
}
 
int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	
	cin >> n;
	fill(ans, ans + n, -1);
	
	for(int i = 0;i < n;i++){
		long long x, y, r; cin >> x >> y >> r;
		x += (1LL << 31LL); y += (1LL << 31LL);
		arr[i] = {x, y, r, i};
		sorted[i] = {x, y, r, i};
	}
	
	sort(sorted,sorted+n,comp);
	
	for(int i = 0;i < n;i++){
		Circle C = sorted[i];
		
		if(ans[C.id] != -1) continue;
				
		if(gridSize > 2 * C.r){
			buildGrid(C.r);
		}
		
		long long xSquare = C.x / gridSize;
		long long ySquare = C.y / gridSize;
		
		for(long long x = xSquare - 2;x <= xSquare + 2;x++){
			for(long long y = ySquare - 2;y <= ySquare + 2;y++){
				vector<int> &points = GRID[ii(x,y)];
				
				for(int p = 0;p < (int) points.size();p++){
					if(intersect(arr[points[p]],C)){
						ans[points[p]] = C.id;
												
						points[p] = points.back();
						points.pop_back();
						p--;
					}
				}
			}
		}
	}
	
	for(int i = 0;i < n;i++) cout << ans[i] + 1 << " ";
}

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