Submission #107111

#	Time	Username	Problem	Language	Result	Execution time	Memory
107111		tictaccat	Circle selection (APIO18_circle_selection)	C++14	49 / 100	3066 ms	263924 KiB

circle_selection

#include <bits/stdc++.h>

using namespace std;

#define int long long

const int MAX = 3e5;

int n;
int gridSize;

vector<pair<int,pair<int,int>>> circles(MAX);
unordered_map<int,vector<int>> grid;
set<pair<int,int>> cur;
vector<int> elim(MAX,-1);

int dist(pair<int,int> p1, pair<int,int> p2) {return (p2.first-p1.first)*(p2.first-p1.first) + (p2.second-p1.second)*(p2.second-p1.second);}
bool intsct(pair<int,pair<int,int>> c1, pair<int,pair<int,int>> c2) {return dist(c1.second,c2.second) <= (c1.first+c2.first)*(c1.first+c2.first);}
int toInt(int xbin, int ybin) {return xbin + ybin * (int)(5e9);}

void makeGrid() {
    grid.clear();
    grid.reserve(count(elim.begin(),elim.end(),-1));
    for (int i = 0; i < n; i++) {
        if (elim[i] != -1) continue;
        auto c = circles[i]; auto p = c.second;
        int xbin = p.first/gridSize; int ybin = p.second/gridSize;
       // cout << toInt(p) << "\n";
        //assert (toInt(p) < numeric_limits<long long>::max());
        if (grid.count(toInt(xbin,ybin)) == 0) grid[toInt(xbin,ybin)] = {i};
        else grid[toInt(xbin,ybin)].push_back(i);
    }
}

main() {

    // cin.tie(0);
    // ios::sync_with_stdio(false);

    cin >> n;

    for (int i = 0; i < n; i++) {
        int x,y,r; cin >> x >> y >> r;
        circles[i] = make_pair(r,make_pair(x,y));
        cur.insert(make_pair(-r,i));
    }
    
    gridSize = 1e18;
    makeGrid();

    while (cur.size() > 0) {
        int i = cur.begin()->second;
        auto top = circles[i]; auto p = top.second; 
        if (top.first < gridSize/2) {
            gridSize = top.first;
            makeGrid();
        }
        int xbinTop = p.first/gridSize; int ybinTop = p.second/gridSize;
        for (int xbin = xbinTop-2; xbin <= xbinTop + 2; xbin++) {
            for (int ybin = ybinTop-2; ybin <= ybinTop + 2; ybin++) {
                for (int j: grid[toInt(xbin,ybin)]) {
                    if (elim[j] == -1 && intsct(top,circles[j])) {
                    //    cout << i+1 << " " << j+1 << "\n";
                        elim[j] = i;
                        assert(cur.count(make_pair(-circles[j].first,j))  == 1);
                        cur.erase(make_pair(-circles[j].first,j)); 
                    }
                }
            }
        }
      ///  break;
    }
    
    for (int i = 0; i < n; i++) {
        cout << elim[i]+1 << " ";
    }

    cout << "\n";

    return 0;
}

Compilation message (stderr)

circle_selection.cpp:35:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main() {
      ^

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