Submission #250927

#	Time	Username	Problem	Language	Result	Execution time	Memory
250927		nvmdava	Circle selection (APIO18_circle_selection)	C++17	100 / 100	2405 ms	42544 KiB

circle_selection

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ff first
#define ss second
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define N 300005
const ll MOD = 1000000007;
const int INF = 0x3f3f3f3f;

int x[N], y[N], r[N];
int lr = 2'000'000'002;
int ans[N];
int n;

vector<pair<int, int> > v;

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

inline ll pw(ll a){
    return a * a;
}

bool check(int i, int j){
    return pw(x[i] - x[j]) + pw(y[i] - y[j]) <= pw(r[i] + r[j]);
}

inline int divv(int a, int b){
    return a / b - (a < 0 && a % b != 0);
}

void reset(int r){
    id.clear();
    for(int i = 1; i <= n; ++i){
        if(ans[i]) continue;
        int xx = divv(x[i], r);
        int yy = divv(y[i], r);
        id[{xx, yy}].push_back(i);
    }
}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    cin>>n;
    for(int i = 1; i <= n; ++i){
        cin>>x[i]>>y[i]>>r[i];
        v.push_back({-r[i], i});
    }


    sort(v.begin(), v.end());

    for(auto& w : v){
        if(ans[w.ss]) continue;
        if(lr >= 2 * r[w.ss])
            reset(lr = r[w.ss]);
        int xx = divv(x[w.ss], lr);
        int yy = divv(y[w.ss], lr);
        for(int dx = -2; dx <= 2; ++dx){
            for(int dy = -2; dy <= 2; ++dy){
                auto it = id.find({xx + dx, yy + dy});
                if(it == id.end()) continue;
                for(int i = 0; i < it -> ss.size(); ++i){
                    if(check(it -> ss[i], w.ss)){
                        ans[it -> ss[i]] = w.ss;
                        swap(it -> ss[i], it -> ss.back());
                        it -> ss.pop_back();
                        --i;
                    }
                }
                if(it -> ss.empty())
                    id.erase(it);

            }
        }
    }

    for(int i = 1; i <= n; ++i)
        cout<<ans[i]<<' ';
}

Compilation message (stderr)

circle_selection.cpp: In function 'int main()':
circle_selection.cpp:66:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
                 for(int i = 0; i < it -> ss.size(); ++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