Submission #719340

#	Time	Username	Problem	Language	Result	Execution time	Memory
719340		rainboy	Min-max tree (BOI18_minmaxtree)	C11	22 / 100	96 ms	17352 KiB

minmaxtree

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define N	70000
#define M	70000

unsigned int X = 12345;

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

int *ej[N], eo[N], *ei[M], eo_[M];

void append(int **ej, int *eo, int i, int j) {
	int o = eo[i]++;

	if (o >= 2 && (o & o - 1) == 0)
		ej[i] = (int *) realloc(ej[i], o * 2 * sizeof *ej[i]);
	ej[i][o] = j;
}

int pp[N], dd[N];

void dfs1(int p, int i, int d) {
	int o;

	pp[i] = p, dd[i] = d;
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		if (j != p)
			dfs1(i, j, d + 1);
	}
}

char type[M]; int ii[M], jj[M], ww[M];

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)
			if (ww[hh[j]] == ww[h])
				j++;
			else if (ww[hh[j]] < ww[h]) {
				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;
	}
}

char used[N]; int pp_[N];

int find_(int i) {
	return !used[i] ? i : (pp_[i] = find_(pp_[i]));
}

int ds[M];

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;
}

int xx[N], hh1[N], hh2[N]; char visited[M];

void dfs2(int p, int h) {
	int o;

	if (p != -1)
		xx[p] = ww[h];
	if (visited[h])
		return;
	visited[h] = 1;
	for (o = eo_[h]; o--; ) {
		int i = ei[h][o], h_ = h ^ hh1[i] ^ hh2[i];

		if (i != p)
			dfs2(i, h_);
	}
}

int main() {
	static int hh[M];
	int n, m, h, h_, i, j;

	scanf("%d", &n);
	for (i = 0; i < n; i++)
		ej[i] = (int *) malloc(2 * sizeof *ej[i]);
	for (h = 0; h < n - 1; h++) {
		scanf("%d%d", &i, &j), i--, j--;
		append(ej, eo, i, j), append(ej, eo, j, i);
	}
	dfs1(-1, 0, 0);
	scanf("%d", &m);
	for (h = 0; h < m; h++) {
		static char s[2];

		scanf("%s%d%d%d", s, &ii[h], &jj[h], &ww[h]), ii[h]--, jj[h]--;
		type[h] = s[0] == 'm' ? 0 : 1;
	}
	for (h = 0; h < m; h++)
		hh[h] = h;
	sort(hh, 0, m);
	memset(used, 0, n * sizeof *used);
	memcpy(pp_, pp, n * sizeof *pp_);
	memset(hh1, -1, n * sizeof *hh1);
	for (h = m - 1; h >= 0; h--) {
		h_ = hh[h];
		if (type[h_] == 0) {
			i = ii[h_], j = jj[h_];
			while (1) {
				i = find_(i), j = find_(j);
				if (i == j)
					break;
				if (dd[i] > dd[j])
					hh1[i] = h_, used[i] = 1;
				else
					hh1[j] = h_, used[j] = 1;
			}
		}
	}
	memset(used, 0, n * sizeof *used);
	memcpy(pp_, pp, n * sizeof *pp_);
	memset(hh2, -1, n * sizeof *hh2);
	for (h = 0; h < m; h++) {
		h_ = hh[h];
		if (type[h_] == 1) {
			i = ii[h_], j = jj[h_];
			while (1) {
				i = find_(i), j = find_(j);
				if (i == j)
					break;
				if (dd[i] > dd[j])
					hh2[i] = h_, used[i] = 1;
				else
					hh2[j] = h_, used[j] = 1;
			}
		}
	}
	for (i = 0; i < n; i++)
		if (hh1[i] == -1)
			hh1[i] = hh2[i];
		else if (hh2[i] == -1)
			hh2[i] = hh1[i];
	for (h = 0; h < m; h++)
		ei[h] = (int *) malloc(2 * sizeof *ei[h]);
	for (i = 0; i < n; i++)
		if (hh1[i] != -1)
			append(ei, eo_, hh1[i], i), append(ei, eo_, hh2[i], i);
	memset(ds, -1, m * sizeof *ds);
	for (i = 0; i < n; i++)
		if (hh1[i] != -1 && !join(hh1[i], hh2[i]) && !visited[hh1[i]])
			dfs2(-1, hh1[i]);
	for (i = 1; i < n; i++)
		printf("%d %d %d\n", pp[i] + 1, i + 1, xx[i]);
	return 0;
}

Compilation message (stderr)

minmaxtree.c: In function 'append':
minmaxtree.c:19:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   19 |  if (o >= 2 && (o & o - 1) == 0)
      |                     ~~^~~
minmaxtree.c: In function 'main':
minmaxtree.c:108:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  108 |  scanf("%d", &n);
      |  ^~~~~~~~~~~~~~~
minmaxtree.c:112:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  112 |   scanf("%d%d", &i, &j), i--, j--;
      |   ^~~~~~~~~~~~~~~~~~~~~
minmaxtree.c:116:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  116 |  scanf("%d", &m);
      |  ^~~~~~~~~~~~~~~
minmaxtree.c:120:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  120 |   scanf("%s%d%d%d", s, &ii[h], &jj[h], &ww[h]), ii[h]--, jj[h]--;
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 7
• Subtask 2: 22 / 22
• Subtask 3: 0 / 29
• Subtask 4: 0 / 42