Submission #405183

#	Time	Username	Problem	Language	Result	Execution time	Memory
405183		rainboy	Roller Coaster Railroad (IOI16_railroad)	C11	100 / 100	212 ms	12824 KiB

railroad

#include "railroad_c.h"
#include <string.h>

#define N	200001
#define INF	0x3f3f3f3f

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

unsigned int X = 12345;

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

int xx[N * 2], uu[N * 2 - 1], vv[N * 2 - 1], ww[N * 2 - 1];

int compare_x(int i, int j) {
	return xx[i] != xx[j] ? xx[i] - xx[j] : (i & 1) - (j & 1);
}

int compare_w(int h1, int h2) {
	return ww[h1] - ww[h2];
}

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

		while (j < k) {
			int c = compare(ii[j], i_);

			if (c == 0)
				j++;
			else if (c < 0) {
				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, compare);
		l = k;
	}
}

int ds[N];

int find(int i) {
	return ds[i] < 0 ? i : (ds[i] = find(ds[i]));
}

int join(int i, int j) {
	i = find(i);
	j = find(j);
	if (i == j)
		return 0;
	if (ds[i] > ds[j])
		ds[i] = j;
	else {
		if (ds[i] == ds[j])
			ds[i]--;
		ds[j] = i;
	}
	return 1;
}

long long plan_roller_coaster(int n, int *aa, int *bb) {
	static int hh[N * 2 - 1], ii[N * 2];
	int m, h, h_, i, j, d;
	long long ans;

	for (i = 0; i < n; i++)
		xx[i << 1 | 0] = bb[i], xx[i << 1 | 1] = aa[i];
	xx[n << 1 | 0] = 0, xx[n << 1 | 1] = INF, n++;
	for (i = 0; i < n * 2; i++)
		ii[i] = i;
	sort(ii, 0, n * 2, compare_x);
	memset(ds, -1, n * sizeof *ds);
	ans = 0;
	for (h = 0, d = 0; h < n * 2; h++) {
		i = ii[h];
		d += (i & 1) == 0 ? 1 : -1;
		if (h + 1 < n * 2) {
			j = ii[h + 1];
			if (d < 0)
				ans += (long long) -d * (xx[j] - xx[i]);
			if (d != 0 && h + 1 < n * 2)
				join(i >> 1, j >> 1);
		}
	}
	m = 0;
	for (h = 1; h < n * 2; h++) {
		i = ii[h], j = ii[h - 1];
		if (find(i >> 1) != find(j >> 1))
			uu[m] = i >> 1, vv[m] = j >> 1, ww[m] = xx[i] - xx[j], m++;
	}
	for (h = 0; h < m; h++)
		hh[h] = h;
	sort(hh, 0, m, compare_w);
	for (h = 0; h < m; h++) {
		h_ = hh[h];
		if (join(uu[h_], vv[h_]))
			ans += ww[h_];
	}
	return ans;
}

• Subtask 1: 11 / 11
• Subtask 2: 23 / 23
• Subtask 3: 30 / 30
• Subtask 4: 36 / 36