Submission #745239

#	Time	Username	Problem	Language	Result	Execution time	Memory
745239		rainboy	Roadside Advertisements (NOI17_roadsideadverts)	C11	100 / 100	91 ms	11340 KiB

roadsideadverts

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

#define N	50000
#define M	5

unsigned int X = 12345;

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

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

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

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

int dd[N], pp[N], qq[N], xx[N];

int dfs1(int p, int i, int d, int x) {
	int o, s, k_, j_;

	pp[i] = p, dd[i] = d, xx[i] = x;
	s = 1, k_ = 0, j_ = -1;
	for (o = eo[i]; o--; ) {
		int j = ej[i][o], w = ew[i][o];

		if (j != p) {
			int k = dfs1(i, j, d + 1, x + w);

			s += k;
			if (k_ < k)
				k_ = k, j_ = j;
		}
	}
	qq[i] = j_;
	return s;
}

int ta[N], tb[N];

void dfs2(int p, int i, int q) {
	static int time;
	int o, j_;

	ta[i] = time++;
	j_ = qq[i], qq[i] = q;
	if (j_ != -1)
		dfs2(i, j_, q);
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		if (j != p && j != j_)
			dfs2(i, j, j);
	}
	tb[i] = time;
}

int lca(int i, int j) {
	while (qq[i] != qq[j])
		if (dd[qq[i]] > dd[qq[j]])
			i = pp[qq[i]];
		else
			j = pp[qq[j]];
	return dd[i] < dd[j] ? i : j;
}

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

		while (j < k)
			if (ta[ii[j]] == ta[i_])
				j++;
			else if (ta[ii[j]] < ta[i_]) {
				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);
		l = k;
	}
}

int main() {
	int n, q, h, i, j, w;

	scanf("%d", &n);
	for (i = 0; i < n; i++) {
		ej[i] = (int *) malloc(2 * sizeof *ej[i]);
		ew[i] = (int *) malloc(2 * sizeof *ew[i]);
	}
	for (h = 0; h < n - 1; h++) {
		scanf("%d%d%d", &i, &j, &w);
		append(i, j, w), append(j, i, w);
	}
	dfs1(-1, 0, 0, 0);
	dfs2(-1, 0, 0);
	scanf("%d", &q);
	while (q--) {
		static int ii[M];
		int ans;

		for (h = 0; h < M; h++)
			scanf("%d", &ii[h]);
		sort(ii, 0, M);
		ans = 0;
		for (h = 0; h < M; h++)
			ans += xx[ii[h]];
		for (h = 0; h < M; h++)
			ans -= xx[lca(ii[h], ii[(h + 1) % M])];
		printf("%d\n", ans);
	}
	return 0;
}

Compilation message (stderr)

roadsideadverts.c: In function 'append':
roadsideadverts.c:18:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   18 |  if (o >= 2 && (o & o - 1) == 0) {
      |                     ~~^~~
roadsideadverts.c: In function 'main':
roadsideadverts.c:97:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   97 |  scanf("%d", &n);
      |  ^~~~~~~~~~~~~~~
roadsideadverts.c:103:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  103 |   scanf("%d%d%d", &i, &j, &w);
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~
roadsideadverts.c:108:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  108 |  scanf("%d", &q);
      |  ^~~~~~~~~~~~~~~
roadsideadverts.c:114:4: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  114 |    scanf("%d", &ii[h]);
      |    ^~~~~~~~~~~~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 23 / 23
• Subtask 3: 40 / 40
• Subtask 4: 30 / 30