Submission #727920

#	Time	Username	Problem	Language	Result	Execution time	Memory
727920		rainboy	Sightseeing (NOI14_sightseeing)	C11	25 / 25	2788 ms	185044 KiB

sightseeing

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

#define N	500000
#define M	5000000
#define INF	0x3f3f3f3f

unsigned int X = 12345;

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

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;
	}
}

int ds[N], ww_[N];

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

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

int query(int i, int j) {
	int w = INF; 

	while (i != j)
		if (ww_[i] > ww_[j])
			w = ww_[i], i = ds[i];
		else
			w = ww_[j], j = ds[j];
	return w;
}

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

	scanf("%d%d%d", &n, &m, &q);
	for (h = 0; h < m; h++) {
		scanf("%d%d%d", &ii[h], &jj[h], &ww[h]), ii[h]--, jj[h]--;
		hh[h] = h;
	}
	sort(hh, 0, m);
	memset(ds, -1, n * sizeof *ds), memset(ww_, -1, n * sizeof *ww_);
	for (h = m - 1; h >= 0; h--) {
		h_ = hh[h];
		join(ii[h_], jj[h_], ww[h_]);
	}
	while (q--) {
		scanf("%d", &i), i--;
		printf("%d\n", query(0, i));
	}
	return 0;
}

Compilation message (stderr)

sightseeing.c: In function 'main':
sightseeing.c:70:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   70 |  scanf("%d%d%d", &n, &m, &q);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~
sightseeing.c:72:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   72 |   scanf("%d%d%d", &ii[h], &jj[h], &ww[h]), ii[h]--, jj[h]--;
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
sightseeing.c:82:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   82 |   scanf("%d", &i), i--;
      |   ^~~~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 5 / 5
• Subtask 3: 6 / 6
• Subtask 4: 10 / 10