Submission #733456

#	Time	Username	Problem	Language	Result	Execution time	Memory
733456		rainboy	Climbers (RMI18_climbers)	C11	55 / 100	429 ms	524288 KiB

climbers

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

#define N	5000
#define N_	(N * N)
#define INF	0x3f3f3f3f3f3f3f3fLL

int abs_(int a) { return a > 0 ? a : -a; }

int contains(int a, int b, int c) {
	int tmp;

	if (a > b)
		tmp = a, a = b, b = tmp;
	return a <= c && c <= b;
}

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;
}

long long dd[N_]; int iq[N_ + 1], pq[N_], cnt;

int lt(int i, int j) { return dd[i] < dd[j]; }

int p2(int p) {
	return (p *= 2) > cnt ? 0 : (p < cnt && lt(iq[p + 1], iq[p]) ? p + 1 : p);
}

void pq_up(int i) {
	int p, q, j;

	for (p = pq[i]; (q = p / 2) && lt(i, j = iq[q]); p = q)
		iq[pq[j] = p] = j;
	iq[pq[i] = p] = i;
}

void pq_dn(int i) {
	int p, q, j;

	for (p = pq[i]; (q = p2(p)) && lt(j = iq[q], i); p = q)
		iq[pq[j] = p] = j;
	iq[pq[i] = p] = i;
}

void pq_add_last(int i) {
	iq[pq[i] = ++cnt] = i;
}

int pq_remove_first() {
	int i = iq[1], j = iq[cnt--];

	if (j != i)
		pq[j] = 1, pq_dn(j);
	pq[i] = 0;
	return i;
}

int main() {
	static int aa[N];
	int n, n_, i, i_, j, j_, o;

	scanf("%d", &n), n_ = n * n;
	for (i = 0; i < n; i++)
		scanf("%d", &aa[i]);
	for (i = 0; i < n_; i++) {
		ej[i] = (int *) malloc(2 * sizeof *ej[i]);
		ew[i] = (int *) malloc(2 * sizeof *ew[i]);
	}
	for (i = 0; i < n; i++)
		for (j = 0; j + 1 < n; j++)
			if (contains(aa[j], aa[j + 1], aa[i])) {
				if (i > 0) {
					if (contains(aa[j], aa[j + 1], aa[i - 1]))
						append(i * n + j, (i - 1) * n + j, abs_(aa[i - 1] - aa[i]));
					if (contains(aa[i], aa[i - 1], aa[j]))
						append(i * n + j, j * n + (i - 1), abs_(aa[j] - aa[i]));
					if (contains(aa[i], aa[i - 1], aa[j + 1]))
						append(i * n + j, (j + 1) * n + (i - 1), abs_(aa[j + 1] - aa[i]));
				}
				if (i + 1 < n) {
					if (contains(aa[j], aa[j + 1], aa[i + 1]))
						append(i * n + j, (i + 1) * n + j, abs_(aa[i + 1] - aa[i]));
					if (contains(aa[i], aa[i + 1], aa[j]))
						append(i * n + j, j * n + i, abs_(aa[j] - aa[i]));
					if (contains(aa[i], aa[i + 1], aa[j + 1]))
						append(i * n + j, (j + 1) * n + i, abs_(aa[j + 1] - aa[i]));
				}
			}
	memset(dd, 0x3f, n_ * sizeof *dd);
	dd[0 * n + (n - 2)] = 0, pq_add_last(0 * n + (n - 2));
	while (cnt) {
		i_ = pq_remove_first(), i = i_ / n, j = i_ % n;
		if (i == j || i == j + 1) {
			printf("%lld\n", dd[i_]);
			return 0;
		}
		for (o = eo[i_]; o--; ) {
			int w;
			long long d;

			j_ = ej[i_][o], w = ew[i_][o], d = dd[i_] + w;
			if (dd[j_] > d) {
				if (dd[j_] == INF)
					pq_add_last(j_);
				dd[j_] = d, pq_up(j_);
			}
		}
	}
	printf("NO\n");
	return 0;
}

Compilation message (stderr)

climbers.c: In function 'append':
climbers.c:24:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   24 |  if (o >= 2 && (o & o - 1) == 0) {
      |                     ~~^~~
climbers.c: In function 'main':
climbers.c:72:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   72 |  scanf("%d", &n), n_ = n * n;
      |  ^~~~~~~~~~~~~~~
climbers.c:74:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   74 |   scanf("%d", &aa[i]);
      |   ^~~~~~~~~~~~~~~~~~~

• Subtask 1: 15 / 25
• Subtask 2: 25 / 25
• Subtask 3: 15 / 50