Submission #160535

#	Time	Username	Problem	Language	Result	Execution time	Memory
160535		Minnakhmetov	Circle selection (APIO18_circle_selection)	C++14	100 / 100	2536 ms	54616 KiB

circle_selection

#include <bits/stdc++.h>
    
#define ll long long
#define all(aaa) aaa.begin(), aaa.end()
  
using namespace std;

struct C {
    ll x, y, r, i;
};

const int N = 3e5 + 5, INF = 1e9;
map<pair<ll, ll>, vector<int>> mp;
bool used[N];
C cir[N];
int n;
int ans[N];

bool check(const C &a, const C &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);
}

void build(int r) {
    mp.clear();
    for (int i = 0; i < n; i++) {
        if (!used[i]) {
            mp[{cir[i].x / r, cir[i].y / r}].push_back(i);
        }
    }
}
 
signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(NULL);

    cin >> n;

    int cur = 0;

    for (int i = 0; i < n; i++) {
        cin >> cir[i].x >> cir[i].y >> cir[i].r;
        cir[i].x += INF;
        cir[i].y += INF;
        cir[i].i = i;
    }

    sort(cir, cir + n, [](const C &a, const C &b) {
        return a.r == b.r ? a.i < b.i : a.r > b.r;
    });

    cur = cir[0].r;

    build(cur);

    for (int i = 0; i < n; i++) {
        if (!used[i]) {
            // cout << cir[i].x << " " << cir[i].y << " " << cir[i].r << "\n";

            if (cir[i].r * 2 < cur) {
                cur = cir[i].r;
                build(cur);
            }

            int x = cir[i].x / cur,
                y = cir[i].y / cur;

            for (int j = x - 2; j <= x + 2; j++) {
                for (int k = y - 2; k <= y + 2; k++) {
                    if (mp.count({j, k})) {
                        vector<int> &v = mp[{j, k}];
                        for (int h = 0; h < v.size(); h++) {
                            if (check(cir[i], cir[v[h]])) {
                                ans[cir[v[h]].i] = cir[i].i;
                                used[v[h]] = 1;
                                swap(v.back(), v[h]);
                                v.pop_back();
                                h--;
                            }
                        }
                    }
                    
                }
            }
        }
    }

    for (int i = 0; i < n; i++) {
        cout << ans[i] + 1 << " ";
    }
 
    return 0;
}

Compilation message (stderr)

circle_selection.cpp: In function 'int main()':
circle_selection.cpp:72:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
                         for (int h = 0; h < v.size(); h++) {
                                         ~~^~~~~~~~~~

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