Submission #87164

#	Time	Username	Problem	Language	Result	Execution time	Memory
87164		fedoseevtimofey	Circle selection (APIO18_circle_selection)	C++14	100 / 100	2529 ms	411756 KiB

circle_selection

#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef long double ld;
 
int n;
vector <int> x, y, r;
vector <int> _kill;

void init() {
    cin >> n;
    x.resize(n);
    y.resize(n);
    r.resize(n);
    for (int i = 0; i < n; ++i) {
        cin >> x[i] >> y[i] >> r[i];
    }
}
 
bool inter(int i, int j) {
    return (ll)(x[i] - x[j]) * (x[i] - x[j]) + (ll)(y[i] - y[j]) * (y[i] - y[j]) <= (ll)(r[i] + r[j]) * (r[i] + r[j]);
}
 
map <pair <int, int>, vector <int>> who;
 
 
void rebuild(int B) {
    who.clear();
    for (int i = 0; i < n; ++i) {
        if (_kill[i] != -1) continue;
        int xx = x[i] / B;
        int yy = y[i] / B;
        who[make_pair(xx, yy)].push_back(i);
    }
}
 
void solve() {
    _kill.resize(n, -1);
    vector <int> idx(n);
    iota(idx.begin(), idx.end(), 0);
    sort(idx.begin(), idx.end(), [&] (int i, int j) {
        if (r[i] != r[j]) return r[i] > r[j];
        return i < j;
    });
    int uk = 0;
    int B = 2e9 + 7;
    while (true) {
        while (uk < n && _kill[idx[uk]] != -1) ++uk;
        if (uk == n) break;
        int cur = idx[uk];
        if ((r[cur] << 1) <= B) {
            B = r[cur];
            rebuild(B);
        }
        _kill[cur] = cur;
        int xx = x[cur] / B;
        int yy = y[cur] / B;
        for (int cx = xx - 2; cx <= xx + 2; ++cx) {
            for (int cy = yy - 2; cy <= yy + 2; ++cy) {
                if (who.count(make_pair(cx, cy))) {
                    for (auto j : who[make_pair(cx, cy)]) {
                        if (_kill[j] == -1 && inter(cur, j)) {
                            _kill[j] = cur;
                        }
                    }
                }
            }
        }
    }
    for (int i = 0; i < n; ++i) {
        cout << _kill[i] + 1 << ' ';
    }
}
 
int main() {
    ios_base::sync_with_stdio(false); cin.tie(0); cout.setf(ios::fixed); cout.precision(20);
    #ifdef LOCAL
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    #endif
    init();
    solve();
}

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