Submission #381192

#	Time	Username	Problem	Language	Result	Execution time	Memory
381192		rainboy	Circle selection (APIO18_circle_selection)	C11	7 / 100	208 ms	16108 KiB

circle_selection

#include <stdio.h>

#define N	300000

unsigned int X = 12345;

int rand_() {
	return (X *= 3) >> 1;
}

int xx[N], yy[N], rr_[N];

void sort(int *ii, int l, int r) {
	while (l < r) {
		int i = l, j = l, k = r, i_ = ii[l + rand_() % (r - l)], tmp;

		while (j < k)
			if (rr_[ii[j]] == rr_[i_])
				j++;
			else if (rr_[ii[j]] < rr_[i_]) {
				tmp = ii[i], ii[i] = ii[j], ii[j] = tmp;
				i++, j++;
			} else {
				k--;
				tmp = ii[j], ii[j] = ii[k], ii[k] = tmp;
			}
		sort(ii, l, i);
		l = k;
	}
}

int zz[1 + N], ll[1 + N], rr[1 + N], ii_[1 + N], u_, l_, r_;

int node(int i) {
	static int _ = 1;

	zz[_] = rand_();
	ii_[_] = i;
	return _++;
}

void split(int u, int x) {
	int x_;

	if (u == 0) {
		l_ = r_ = 0;
		return;
	}
	x_ = xx[u] - rr[u];
	if (x_ < x) {
		split(rr[u], x);
		rr[u] = l_, l_ = u;
	} else if (x_ > x) {
		split(ll[u], x);
		ll[u] = r_, r_ = u;
	}
}

int merge(int u, int v) {
	if (u == 0)
		return v;
	if (v == 0)
		return u;
	if (zz[u] < zz[v]) {
		rr[u] = merge(rr[u], v);
		return u;
	} else {
		ll[v] = merge(u, ll[v]);
		return v;
	}
}

int first(int u) {
	return ll[u] == 0 ? u : first(ll[u]);
}

int last(int u) {
	return rr[u] == 0 ? u : last(rr[u]);
}

int main() {
	static int ii[N], pp[N];
	static char used[N];
	int n, i;

	scanf("%d", &n);
	for (i = 0; i < n; i++)
		scanf("%d%d%d", &xx[i], &yy[i], &rr_[i]);
	if (n <= 5000) {
		while (1) {
			int i_;

			i_ = -1;
			for (i = 0; i < n; i++)
				if (!used[i] && (i_ == -1 || rr_[i_] < rr_[i]))
					i_ = i;
			if (i_ == -1)
				break;
			for (i = 0; i < n; i++) {
				long long x = xx[i] - xx[i_], y = yy[i] - yy[i_], r = rr_[i] + rr_[i_];

				if (!used[i] && x * x + y * y <= r * r)
					used[i] = 1, pp[i] = i_;
			}
		}
	} else {
		for (i = 0; i < n; i++)
			ii[i] = i;
		sort(ii, 0, n);
		for (i = n - 1; i >= 0; i--) {
			int i_ = ii[i], p, q;

			split(u_, xx[i_] - rr_[i_]);
			p = l_ ? ii_[last(l_)] : -1, q = r_ ? ii_[first(r_)] : -1;
			if (p != -1 && xx[p] + rr_[p] < xx[i_] - rr_[i_])
				p = -1;
			if (q != -1 && xx[q] - rr_[q] > xx[i_] - rr_[i_])
				q = -1;
			if (p == -1 && q == -1)
				pp[i_] = i_, u_ = merge(merge(l_, node(i_)), r_);
			else
				pp[i_] = q == -1 || p != -1 && (rr_[p] > rr_[q] || rr_[p] == rr_[q] && p > q) ? p : q;
		}
	}
	for (i = 0; i < n; i++)
		printf("%d ", pp[i] + 1);
	printf("\n");
	return 0;
}

Compilation message (stderr)

circle_selection.c: In function 'main':
circle_selection.c:122:73: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  122 |     pp[i_] = q == -1 || p != -1 && (rr_[p] > rr_[q] || rr_[p] == rr_[q] && p > q) ? p : q;
      |                                                        ~~~~~~~~~~~~~~~~~^~~~~~~~
circle_selection.c:122:33: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  122 |     pp[i_] = q == -1 || p != -1 && (rr_[p] > rr_[q] || rr_[p] == rr_[q] && p > q) ? p : q;
      |                         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
circle_selection.c:86:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   86 |  scanf("%d", &n);
      |  ^~~~~~~~~~~~~~~
circle_selection.c:88:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   88 |   scanf("%d%d%d", &xx[i], &yy[i], &rr_[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