Submission #711314

#	Time	Username	Problem	Language	Result	Execution time	Memory
711314		rainboy	Bulldozer (JOI17_bulldozer)	C11	0 / 100	6 ms	548 KiB

bulldozer

#include <stdio.h>

#define N	2000
#define M	(N * (N - 1))
#define N_	(1 << 11)	/* N_ = pow2(ceil(log2(N))) */

long long max(long long a, long long b) { return a > b ? a : b; }

unsigned int X = 12345;

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

long long cross(int x1, int y1, int x2, int y2) {
	return (long long) x1 * y2 - (long long) x2 * y1;
}

long long dot(int x1, int y1, int x2, int y2) {
	return (long long) x1 * x2 + (long long) y1 * y2;
}

int xx[N], yy[N], ww[N], ii[N], idx[N], n;
int uu[M], vv[M], xx_[M], yy_[M], hh[M], m;

int compare_h(int h1, int h2) {
	int x1 = xx_[h1], y1 = yy_[h1], s1 = x1 < 0 || x1 == 0 && y1 < 0 ? -1 : 1;
	int x2 = xx_[h2], y2 = yy_[h2], s2 = x2 < 0 || x2 == 0 && y2 < 0 ? -1 : 1;
	long long c;

	if (s1 != s2)
		return s1 - s2;
	c = cross(x1, y1, x2, y2);
	return c == 0 ? 0 : (c < 0 ? -1 : 1);
}

int x_, y_;

int compare_i(int i, int j) {
	long long c, d;

	c = cross(x_, y_, xx[i] - xx[j], yy[i] - yy[j]);
	if (c != 0)
		return c < 0 ? -1 : 1;
	d = dot(x_, y_, xx[i] - xx[j], yy[i] - yy[j]);
	return d == 0 ? 0 : (d < 0 ? -1 : 1);
}

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

		while (j < k) {
			int c = compare_h(hh[j], h);

			if (c == 0)
				j++;
			else if (c < 0) {
				tmp = hh[i], hh[i] = hh[j], hh[j] = tmp;
				i++, j++;
			} else {
				k--;
				tmp = hh[j], hh[j] = hh[k], hh[k] = tmp;
			}
		}
		sort(hh, l, i);
		l = k;
	}
}

long long st[N_ * 2], ss[N_ * 2], pp[N_ * 2], qq[N_ * 2]; int n_;

void pul(int i) {
	int l = i << 1, r = l | 1;

	ss[i] = ss[l] + ss[r];
	pp[i] = max(pp[l], ss[l] + pp[r]);
	qq[i] = max(qq[l] + ss[r], qq[r]);
	st[i] = max(max(st[l], st[r]), qq[l] + pp[r]);
}

void build() {
	int i;

	n_ = 1;
	while (n_ < n)
		n_ <<= 1;
	for (i = 0; i < n; i++) {
		int w = ww[ii[i]];

		ss[n_ + i] = w, st[n_ + i] = pp[n_ + i] = qq[n_ + i] = max(w, 0);
	}
	for (i = n_ - 1; i > 0; i--)
		pul(i);
}

void update(int i, int x) {
	i += n_;
	ss[i] = x, st[i] = pp[i] = qq[i] = max(x, 0);
	while (i > 1)
		pul(i >>= 1);
}

void bubble(int i) {
	int h, j;

	h = idx[i];
	while (h + 1 < n && compare_i(i, j = ii[h + 1]) > 0) {
		ii[idx[j] = h] = j, ii[idx[i] = h + 1] = i;
		update(h, ww[j]), update(h + 1, ww[i]);
		h++;
	}
	while (h > 0 && compare_i(i, j = ii[h - 1]) < 0) {
		ii[idx[j] = h] = j, ii[idx[i] = h - 1] = i;
		update(h, ww[j]), update(h - 1, ww[i]);
		h--;
	}
}

int main() {
	int h, h_, i, j;
	long long ans;

	scanf("%d", &n);
	for (i = 0; i < n; i++)
		scanf("%d%d%d", &xx[i], &yy[i], &ww[i]);
	m = 0;
	for (i = 0; i < n; i++)
		for (j = 0; j < n; j++)
			if (i != j)
				uu[m] = i, vv[m] = j, xx_[m] = xx[j] - xx[i], yy_[m] = yy[j] - yy[i], m++;
	for (h = 0; h < m; h++)
		hh[h] = h;
	sort(hh, 0, m);
	for (i = 0; i < n; i++)
		ii[idx[i] = i] = i;
	build();
	x_ = xx_[hh[0]], y_ = yy_[hh[0]];
	for (i = 0; i < n; i++)
		bubble(i);
	ans = 0;
	for (h = 0; h < m; h++) {
		h_ = hh[h], x_ = xx_[h_], y_ = yy_[h_];
		bubble(uu[h_]), bubble(vv[h_]);
		if (h + 1 == m || compare_h(h_, hh[h + 1]) != 0)
			ans = max(ans, st[1]);
	}
	printf("%lld\n", ans);
	return 0;
}

Compilation message (stderr)

bulldozer.c: In function 'compare_h':
bulldozer.c:27:57: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   27 |  int x1 = xx_[h1], y1 = yy_[h1], s1 = x1 < 0 || x1 == 0 && y1 < 0 ? -1 : 1;
      |                                                 ~~~~~~~~^~~~~~~~~
bulldozer.c:28:57: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   28 |  int x2 = xx_[h2], y2 = yy_[h2], s2 = x2 < 0 || x2 == 0 && y2 < 0 ? -1 : 1;
      |                                                 ~~~~~~~~^~~~~~~~~
bulldozer.c: In function 'main':
bulldozer.c:124:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  124 |  scanf("%d", &n);
      |  ^~~~~~~~~~~~~~~
bulldozer.c:126:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  126 |   scanf("%d%d%d", &xx[i], &yy[i], &ww[i]);
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 5
• Subtask 2: 0 / 20
• Subtask 3: 0 / 35
• Subtask 4: 0 / 20
• Subtask 5: 0 / 20