Submission #1196198

#	Time	Username	Problem	Language	Result	Execution time	Memory
1196198		countless	Circle selection (APIO18_circle_selection)	C++20	7 / 100	3095 ms	22568 KiB

circle_selection

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

typedef long long ll;
typedef long double ld;

const ll MOD = 998244353;
const ll INF = 1e18;
const ld EPS = 1e-12;

#define endl "\n"
#define sp <<" "<<
#define REP(i, a, b) for(ll i = a; i < b; i++)
#define dbg(x) cout << #x << " = " << x << endl
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define fast_io() ios_base::sync_with_stdio(false); cin.tie(NULL)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) ((ll)(x).size())

struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        // http://xorshift.di.unimi.it/splitmix64.c
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};

template <typename Key, typename Value>
using hash_map = unordered_map<Key, Value, custom_hash>;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
// uniform_int_distribution<int>(a, b)(rng);
// shuffle(all(a), rng);

struct circle {
    ld x, y, r, j;

    circle(ld x = 0, ld y = 0, ld r = 0) : x(x), y(y), r(r) {;;}

    bool operator<(const circle &other) const {
        if (r == other.r) return j > other.j;
        return r < other.r;
    }
};

void solution() {
    int n; cin >> n;
    vector<circle> a(n);
    REP(i, 0, n) {
        cin >> a[i].x >> a[i].y >> a[i].r;
        a[i].j = i+1;
    }

    vector<int> ans(n+1);
    vector<bool> vis(n+1);
    iota(all(ans), 1);
    sort(rall(a));

    auto intersect = [&](int i, int k) -> bool {
        ld dx = abs(a[i].x - a[k].x);
        ld dy = abs(a[i].y - a[k].y);
        return sqrtl(dx * dx + dy * dy) <= a[i].r + a[k].r;
    };

    REP(i, 0, n) {
        if (vis[a[i].j]) continue;

        REP(k, 0, n) {
            if (vis[a[k].j]) continue;

            if (intersect(i, k)) {
                vis[a[k].j] = true;
                ans[a[k].j] = a[i].j;
            }
        }
    }

    REP(i, 1, n+1) {
        cout << ans[i] << " ";
    }
    cout << endl;
    return;
}

signed main() {
    fast_io();

    solution();

    return 0;
}

// Notes
// is it binsearchable?
// is it greedy?
// is it DP?
// if online round: search OEIS, similar topics

// put observations together
// check for edge cases
// try "dumb" solutions, you're fast enough to rewrite
// clean up the implementation
// keep it simple

// check for overflow
// check for small N
// check for array with same or monotonic a_i

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