Submission #397216

#	Time	Username	Problem	Language	Result	Execution time	Memory
397216		parsabahrami	Circle selection (APIO18_circle_selection)	C++17	7 / 100	3093 ms	327040 KiB

circle_selection

/* There's someone in my head but it's not me */ 
#include <bits/stdc++.h>
 
using namespace std;

typedef long long int ll;
typedef pair<int, int> pii;
 
#define SZ(x)                       (int) x.size()
#define F                           first
#define S                           second

const int N = 3e5 + 10, MOD = 1e9 + 7;
int n, X[N], Y[N], R[N], ord[N], xord[N], pos[N], ret[N];
struct node : set<pii> {
    node *lc, *rc; 

    node() : lc(nullptr), rc(nullptr) {}

    void build(int l = 1, int r = n + 1) {
        if (r - l < 2) return;
        int md = (l + r) >> 1;
        lc = new node(), rc = new node();
        lc->build(l, md), rc->build(md, r);
    }

    void remove(int p, int id, int l = 1, int r = n + 1) {
        this->erase({Y[id], id});
        if (r - l < 2) return;
        int md = (l + r) >> 1;
        if (p < md) lc->remove(p, id, l, md);
        else rc->remove(p, id, md, r);
    }

    int get(ll xl, ll xr, ll yl, ll yr, int l = 1, int r = n + 1) {
        if (xr <= X[xord[l]] || X[xord[r - 1]] + 1 <= xl || this->empty()) return -1;
        if (xl <= X[xord[l]] && X[xord[r - 1]] + 1 <= xr) {
            auto lb = this->lower_bound({yl, -1e9});
            if (lb != this->end() && lb->F <= yr) return lb->S;
            else return -1;
        }
        int md = (l + r) >> 1, a;
        a = lc->get(xl, xr, yl, yr, l, md);
        if (~a) return a;
        return rc->get(xl, xr, yl, yr, md, r);
    }
    
    void ins(int p, int y, int id, int l = 1, int r = n + 1) {
        this->insert({y, id});
        if (r - l < 2) return;
        int md = (l + r) >> 1;
        if (p < md) lc->ins(p, y, id, l, md);
        else rc->ins(p, y, id, md, r);
    }

};
node* seg;

int intersect(int i, int j) {
    ll x1 = X[i], x2 = X[j], y1 = Y[i], y2 = Y[j], r1 = R[i], r2 = R[j];
    return x1 * x1 + x2 * x2 + y1 * y1 + y2 * y2 - r1 * r1 - r2 * r2 <= 2 * (r1 * r2 + x1 * x2 + y1 * y2);
}

int main() {
    scanf("%d", &n);
    for (int i = 1; i <= n; i++) 
        scanf("%d%d%d", &X[i], &Y[i], &R[i]);
    iota(ord + 1, ord + n + 1, 1);
    iota(xord + 1, xord + n + 1, 1);
    sort(ord + 1, ord + n + 1, [&] (int i, int j) { return R[i] == R[j] ? i < j : R[i] > R[j]; });
    sort(xord + 1, xord + n + 1, [&] (int i, int j) { return X[i] < X[j]; });
    seg = new node(); seg->build();
    for (int i = 1; i <= n; i++) {
        seg->ins(i, Y[xord[i]], xord[i]), pos[xord[i]] = i;
    }
    for (int _ = 1; _ <= n; _++) {
        int i = ord[_]; vector<int> ids;
        if (ret[i]) continue;
        for (;;) {
            int id = seg->get(X[i] - 2ll * R[i], X[i] + 2ll * R[i] + 1, Y[i] - 2ll * R[i], Y[i] + 2ll * R[i]);
            if (~id) ids.push_back(id), seg->remove(pos[id], id);
            else break;
        }
        for (int &id : ids) {
            if (intersect(i, id)) ret[id] = i;
            else seg->ins(pos[id], Y[id], id);
        }
    }
    for (int i = 1; i <= n; i++) printf("%d ", ret[i]);
    printf("\n");
    return 0;
}

Compilation message (stderr)

circle_selection.cpp: In function 'int main()':
circle_selection.cpp:65:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   65 |     scanf("%d", &n);
      |     ~~~~~^~~~~~~~~~
circle_selection.cpp:67:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   67 |         scanf("%d%d%d", &X[i], &Y[i], &R[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