Submission #491186

#	Time	Username	Problem	Language	Result	Execution time	Memory
491186		rainboy	Pastiri (COI20_pastiri)	C11	100 / 100	667 ms	64912 KiB

pastiri

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

#define N	500000

int *ej[N], eo[N];

void append(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 ft[N];

void update(int i, int n, int x) {
	while (i < n) {
		ft[i] += x;
		i |= i + 1;
	}
}

int query(int i) {
	int x = 0;

	while (i >= 0) {
		x += ft[i];
		i &= i + 1, i--;
	}
	return x;
}

int dd[N], ta[N], tb[N], qu[N], n, head, cnt; char visited[N];

void dfs_(int i) {
	int o;

	if (visited[i] == 1)
		return;
	if (dd[i] == 0 && visited[i] == 0)
		update(ta[i], n, -1);
	visited[i] = 1;
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		if (dd[j] == dd[i] - 1)
			dfs_(j);
	}
}

void dfs(int p, int i) {
	static int time;
	int o;

	ta[i] = time++;
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		if (j != p)
			dfs(i, j);
	}
	tb[i] = time;
	if (dd[i] == 0 && visited[i] == -1)
		visited[i] = 0, update(ta[i], n, 1);
	if ((p == -1 || dd[i] != dd[p] - 1) && query(tb[i] - 1) - query(ta[i] - 1) > 0)
		qu[cnt++] = i, dfs_(i);
}

int main() {
	int k, h, i, j;

	scanf("%d%d", &n, &k);
	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(i, j), append(j, i);
	}
	for (i = 0; i < n; i++)
		dd[i] = n;
	head = cnt = 0;
	while (k--) {
		scanf("%d", &i), i--;
		dd[i] = 0, qu[head + cnt++] = i;
	}
	while (cnt) {
		int d, o;

		i = qu[cnt--, head++], d = dd[i] + 1;
		for (o = eo[i]; o--; ) {
			j = ej[i][o];
			if (dd[j] > d)
				dd[j] = d, qu[head + cnt++] = j;
		}
	}
	memset(visited, -1, n * sizeof *visited);
	dfs(-1, 0);
	printf("%d\n", cnt);
	for (h = 0; h < cnt; h++)
		printf("%d ", qu[h] + 1);
	printf("\n");
	return 0;
}

Compilation message (stderr)

pastiri.c: In function 'append':
pastiri.c:12:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   12 |  if (o >= 2 && (o & o - 1) == 0)
      |                     ~~^~~
pastiri.c: In function 'main':
pastiri.c:75:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   75 |  scanf("%d%d", &n, &k);
      |  ^~~~~~~~~~~~~~~~~~~~~
pastiri.c:79:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   79 |   scanf("%d%d", &i, &j), i--, j--;
      |   ^~~~~~~~~~~~~~~~~~~~~
pastiri.c:86:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   86 |   scanf("%d", &i), i--;
      |   ^~~~~~~~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 18 / 18
• Subtask 3: 23 / 23
• Subtask 4: 51 / 51