제출 #674256

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
674256		rainboy	Mergers (JOI19_mergers)	C11	100 / 100	591 ms	77296 KiB

mergers

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

#define N	500000

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

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 aa[N], pp[N], ta[N], tb[N], ll[N], rr[N], ll_[N], rr_[N];

void dfs1(int p, int i) {
	static int time;
	int o;

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

		if (j != p)
			dfs1(i, j);
	}
	tb[i] = time;
}

char cut[N];

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

	ll_[i] = ll[aa[i]], rr_[i] = rr[aa[i]];
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		if (j != p) {
			dfs2(i, j);
			ll_[i] = min(ll_[i], ll_[j]), rr_[i] = max(rr_[i], rr_[j]);
			cut[j] = ta[j] <= ll_[j] && rr_[j] < tb[j];
		}
	}
}

int ds[N];

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

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

int main() {
	static int dd[N];
	int n, k, h, i, j, l;

	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++)
		scanf("%d", &aa[i]), aa[i]--;
	dfs1(-1, 0);
	memset(ll, 0x3f, n * sizeof *ll), memset(rr, -1, n * sizeof *rr);
	for (i = 0; i < n; i++)
		ll[aa[i]] = min(ll[aa[i]], ta[i]), rr[aa[i]] = max(rr[aa[i]], ta[i]);
	dfs2(-1, 0);
	memset(ds, -1, n * sizeof *ds);
	for (i = 1; i < n; i++)
		if (!cut[i])
			join(i, pp[i]);
	for (i = 1; i < n; i++)
		if (cut[i])
			dd[find(i)]++, dd[find(pp[i])]++;
	l = 0;
	for (i = 0; i < n; i++)
		if (dd[i] == 1)
			l++;
	printf("%d\n", (l + 1) / 2);
	return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

mergers.c: In function 'append':
mergers.c:15:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   15 |  if (o >= 2 && (o & o - 1) == 0)
      |                     ~~^~~
mergers.c: In function 'main':
mergers.c:78:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   78 |  scanf("%d%d", &n, &k);
      |  ^~~~~~~~~~~~~~~~~~~~~
mergers.c:82:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   82 |   scanf("%d%d", &i, &j), i--, j--;
      |   ^~~~~~~~~~~~~~~~~~~~~
mergers.c:86:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   86 |   scanf("%d", &aa[i]), aa[i]--;
      |   ^~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 24 / 24
• Subtask 3: 14 / 14
• Subtask 4: 22 / 22
• Subtask 5: 30 / 30