Submission #531407

#	Time	Username	Problem	Language	Result	Execution time	Memory
531407		lunchbox	Jakarta Skyscrapers (APIO15_skyscraper)	C11	57 / 100	1077 ms	2256 KiB

skyscraper

#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <string.h>

#define N	30000
#define INF	0x3f3f3f3f
 
unsigned int X;
 
void srand_() {
	struct timeval tv;
 
	gettimeofday(&tv, NULL);
	X = tv.tv_sec ^ tv.tv_usec | 1;
}
 
int rand_() {
	return (X *= 3) >> 1;
}
 
int *ed[N], eo[N];
 
void append(int i, int j) {
	int o = eo[i]++;
 
	if (o >= 2 && (o & o - 1) == 0)
		ed[i] = (int *) realloc(ed[i], o * 2 * sizeof *ed[i]);
	ed[i][o] = j;
}
 
void sort(int *aa, int l, int r) {
	while (l < r) {
		int i = l, j = l, k = r, a_ = aa[l + rand_() % (r - l)], tmp;
 
		while (j < k) {
			int c = aa[j] - a_;
 
			if (c == 0)
				j++;
			else if (c < 0) {
				tmp = aa[i], aa[i] = aa[j], aa[j] = tmp;
				i++, j++;
			} else {
				k--;
				tmp = aa[j], aa[j] = aa[k], aa[k] = tmp;
			}
		}
		sort(aa, l, i);
		l = k;
	}
}
 
int find(int *aa, int n, int a) {
	int lower = 0, upper = n - 1;
 
	while (lower < upper) {
		int t = (lower + upper) / 2;
 
		if (aa[t] < a)
			lower = t + 1;
		else if (aa[t] > a)
			upper = t - 1;
		else
			return 1;
	}
	return 0;
}
 
int dd[N], pq[1 + N], iq[N], cnt;
 
int lt(int u, int v) {
	return dd[u] < dd[v];
}
 
int i2(int i) {
	return (i *= 2) > cnt ? 0 : i < cnt && lt(pq[i + 1], pq[i]) ? i + 1 : i;
}
 
void pq_up(int u) {
	int i, j;
	
	for (i = iq[u]; (j = i / 2) && lt(u, pq[j]); i = j)
		pq[iq[pq[j]] = i] = pq[j];
	pq[iq[u] = i] = u;
}
 
void pq_dn(int u) {
	int i, j;
	
	for (i = iq[u]; (j = i2(i)) && lt(pq[j], u); i = j)
		pq[iq[pq[j]] = i] = pq[j];
	pq[iq[u] = i] = u;
}
 
void pq_add(int u) {
	iq[u] = ++cnt;
	pq_up(u);
}
 
int pq_remove_first() {
	int u = pq[1], v = pq[cnt--];
	
	iq[v] = 1;
	pq_dn(v);
	return u;
}
 
int main() {
	int n, m, i, j, w, d, d_, s, t;
 
	srand_();
	scanf("%d%d", &n, &m);
	for (i = 0; i < n; i++)
		ed[i] = (int *) malloc(2 * sizeof *ed[i]), eo[i] = 0;
	s = t = -1;
	for (i = 0; i < m; i++) {
		scanf("%d%d", &j, &d);
		if (i == 0)
			s = j;
		else if (i == 1)
			t = j;
		append(j, d);
	}
	for (i = 0; i < n; i++) {
		int o = 0;

		sort(ed[i], 0, eo[i]);
		for (j = 0; j < eo[i]; j++)
			if (j == 0 || ed[i][j] != ed[i][j - 1])
				ed[i][o++] = ed[i][j];
		eo[i] = o;
	}
	memset(dd, 0x3f, n * sizeof *dd);
	dd[s] = 0;
	pq_add(s);
	while (cnt) {
		int o;
 
		i = pq_remove_first();
		for (o = eo[i]; o--; ) {
			d = ed[i][o];
			for (w = 0, j = i + d; j < n; j += d) {
				w++;
				d_ = dd[i] + w;
				if (dd[j] == INF) {
					dd[j] = d_;
					pq_add(j);
				} else if (d_ < dd[j]) {
					dd[j] = d_;
					pq_up(j);
				}
				if (find(ed[j], eo[j], d))
					break;
			}
			for (w = 0, j = i - d; j >= 0; j -= d) {
				w++;
				d_ = dd[i] + w;
				if (dd[j] == INF) {
					dd[j] = d_;
					pq_add(j);
				} else if (d_ < dd[j]) {
					dd[j] = d_;
					pq_up(j);
				}
				if (find(ed[j], eo[j], d))
					break;	
			}
		}
	}
	printf("%d\n", dd[t] == INF ? -1 : dd[t]);
}

Compilation message (stderr)

skyscraper.c: In function 'srand_':
skyscraper.c:15:16: warning: suggest parentheses around arithmetic in operand of '|' [-Wparentheses]
   15 |  X = tv.tv_sec ^ tv.tv_usec | 1;
      |      ~~~~~~~~~~^~~~~~~~~~~~
skyscraper.c: In function 'append':
skyscraper.c:27:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   27 |  if (o >= 2 && (o & o - 1) == 0)
      |                     ~~^~~
skyscraper.c: In function 'main':
skyscraper.c:113:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  113 |  scanf("%d%d", &n, &m);
      |  ^~~~~~~~~~~~~~~~~~~~~
skyscraper.c:118:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  118 |   scanf("%d%d", &j, &d);
      |   ^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 12 / 12
• Subtask 3: 14 / 14
• Subtask 4: 21 / 21
• Subtask 5: 0 / 43