Submission #968187

#	Time	Username	Problem	Language	Result	Execution time	Memory
968187		socpite	Circle selection (APIO18_circle_selection)	C++14	100 / 100	1930 ms	49328 KiB

circle_selection

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

const int maxn = 3e5+5;
const int INF = 1e9;

pair<int, int> pt[maxn];
int R[maxn], removed[maxn];

bool cmp(int a, int b){
    return R[a] != R[b] ? R[a] > R[b] : a < b;
}

int n;

bool check(int a, int b){
    return 1LL*(pt[a].first - pt[b].first)*(pt[a].first - pt[b].first) + 1LL*(pt[a].second - pt[b].second)*(pt[a].second - pt[b].second) - 1LL*(R[a] + R[b])*(R[a] + R[b])  <= 0;
}

map<pair<int, int>, vector<int>> mp;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> n;
    vector<int> vec(n);
    iota(vec.begin(), vec.end(), 1);
    int mx = 0;
    for(int i = 1; i <= n; i++){
        cin >> pt[i].first >> pt[i].second >> R[i];
        pt[i].first += INF;
        pt[i].second += INF;
        mx = max(mx, R[i]);
    }
    sort(vec.begin(), vec.end(), cmp);
    for(int i = 1; i <= n; i++){
        mp[{pt[i].first/mx, pt[i].second/mx}].push_back(i);
    }
    for(auto i: vec){
        if(removed[i])continue;
        if(R[i] <= mx/2){
            mx/=2;
            mp.clear();
            for(int j = 1; j <= n; j++){
                if(removed[j])continue;
                mp[{pt[j].first/mx, pt[j].second/mx}].push_back(j);
            }
        }
        for(int j = pt[i].first/mx - 2; j <= pt[i].first/mx + 2; j++){
            for(int k = pt[i].second/mx - 2; k <= pt[i].second/mx + 2; k++){
                if(mp.find(make_pair(j, k)) == mp.end())continue;
                for(auto v: mp[{j, k}])if(!removed[v] && check(v, i))removed[v] = i;
            }
        }
    }
    for(int i = 1; i <= n; i++)cout << removed[i] << " ";
}

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