Submission #479381

#	Time	Username	Problem	Language	Result	Execution time	Memory
479381		rainboy	Transport (COCI19_transport)	C11	130 / 130	269 ms	19628 KiB

Main

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

#define N	100000

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 ij[N], ww[N];
int *eh[N], eo[N], vv[N];

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

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

long long ans;

void remove_(int i, int h) {
	int o;

	for (o = eo[i]; o--; )
		if (eh[i][o] == h) {
			eo[i]--;
			while (o < eo[i])
				eh[i][o] = eh[i][o + 1], o++;
		}
}

int sz[N], c;

void dfs(int p, int i, int n) {
	int o, centroid;

	sz[i] = 1, centroid = 1;
	for (o = eo[i]; o--; ) {
		int h = eh[i][o], j = i ^ ij[h];

		if (j != p) {
			dfs(i, j, n);
			if (sz[j] * 2 > n)
				centroid = 0;
			sz[i] += sz[j];
		}
	}
	if ((n - sz[i]) * 2 > n)
		centroid = 0;
	if (centroid)
		c = i;
}

int rr[N]; long long xx[N * 2]; int ii[N * 2], n_;

void dfs_(int r, int p, int i, long long w, long long x, long long y) {
	int o;

	rr[i] = r;
	xx[i << 1 | 0] = x == w ? w - vv[c] : -1, ii[n_++] = i << 1 | 0;
	xx[i << 1 | 1] = -y, ii[n_++] = i << 1 | 1;
	for (o = eo[i]; o--; ) {
		int h = eh[i][o], j = i ^ ij[h];

		if (j != p)
			dfs_(i == c ? j : r, i, j, w - ww[h] + vv[j], max(x, w - ww[h] + vv[j]), min(y, w - ww[h]));
	}
}

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) {
			int c = xx[ii[j]] != xx[i_] ? (xx[ii[j]] > xx[i_] ? -1 : 1) : (ii[j] & 1) - (i_ & 1);

			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);
		l = k;
	}
}

void cd(int i, int n) {
	static int kk[N];
	int o, h, j, k;

	dfs(-1, i, n), i = c;
	n_ = 0;
	dfs_(i, -1, i, vv[i], vv[i], 0);
	sort(ii, 0, n_);
	for (h = 0, k = 0; h < n_; h++) {
		int i_ = ii[h];

		if ((i_ & 1) == 0)
			kk[rr[i_ >> 1]]++, k++;
		else
			ans += k - kk[rr[i_ >> 1]];
	}
	for (h = 0; h < n_; h++) {
		int i_ = ii[h];

		if ((i_ & 1) == 0)
			kk[rr[i_ >> 1]]--;
	}
	for (o = eo[i]; o--; ) {
		h = eh[i][o], j = i ^ ij[h];
		remove_(j, h), cd(j, sz[j] < sz[i] ? sz[j] : n - sz[i]);
	}
}

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

	scanf("%d", &n);
	for (i = 0; i < n; i++) {
		scanf("%d", &vv[i]);
		eh[i] = (int *) malloc(2 * sizeof *eh[i]);
	}
	for (h = 0; h < n - 1; h++) {
		int w;

		scanf("%d%d%d", &i, &j, &w), i--, j--;
		ij[h] = i ^ j, ww[h] = w;
		append(i, h), append(j, h);
	}
	cd(0, n);
	printf("%lld\n", ans);
	return 0;
}

Compilation message (stderr)

transport.c: In function 'append':
transport.c:21:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   21 |  if (o >= 2 && (o & o - 1) == 0)
      |                     ~~^~~
transport.c: In function 'main':
transport.c:130:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  130 |  scanf("%d", &n);
      |  ^~~~~~~~~~~~~~~
transport.c:132:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  132 |   scanf("%d", &vv[i]);
      |   ^~~~~~~~~~~~~~~~~~~
transport.c:138:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  138 |   scanf("%d%d%d", &i, &j, &w), i--, j--;
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 13 / 13
• Subtask 2: 13 / 13
• Subtask 3: 13 / 13
• Subtask 4: 13 / 13
• Subtask 5: 13 / 13
• Subtask 6: 13 / 13
• Subtask 7: 13 / 13
• Subtask 8: 13 / 13
• Subtask 9: 13 / 13
• Subtask 10: 13 / 13