Submission #829599

#	Time	Username	Problem	Language	Result	Execution time	Memory
829599		rainboy	Airplane (NOI23_airplane)	C11	100 / 100	564 ms	21556 KiB

Main

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

#define N	200000
#define M	400000
#define INF	0x3f3f3f3f

int min(int a, int b) { return a < b ? a : b; }
int max(int a, int b) { return a > b ? a : b; }

unsigned int X = 12345;

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

int n;

int aa[N];

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 (aa[ii[j]] == aa[i_])
				j++;
			else if (aa[ii[j]] < aa[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 *ej[N], eo[N];

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

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

int dd[N];
int qu1[N], cnt1; char in1[N];
int qu2[N], cnt2;

int solve(int t) {
	int h1, h2, i, o;

	memset(dd, 0x3f, n * sizeof *dd);
	memset(in1, 0, n * sizeof *in1);
	dd[0] = 0, in1[0] = 1;
	cnt1 = n, cnt2 = 0, h1 = 0, h2 = 0, i = 0;
	while (h1 < cnt1 || h2 < cnt2) {
		if (h2 == cnt2 || h1 < cnt1 && aa[qu1[h1]] < dd[qu2[h2]]) {
			i = qu1[h1++];
			if (!in1[i])
				continue;
		} else
			i = qu2[h2++];
		if (i == n - 1)
			return 1;
		for (o = eo[i]; o--; ) {
			int j = ej[i][o], d = max(dd[i] + 1, aa[j]);

			if (d + aa[j] <= t && dd[j] > d) {
				dd[j] = d;
				if (d == aa[j])
					in1[j] = 1;
				else
					qu2[cnt2++] = j;
			}
		}
	}
	return 0;
}

int main() {
	static int ii[N];
	int m, h, i, j, lower, upper;

	scanf("%d%d", &n, &m);
	for (i = 0; i < n; i++) {
		scanf("%d", &aa[i]);
		ii[i] = i;
	}
	sort(ii, 0, n);
	for (i = 0; i < n; i++)
		qu1[i] = ii[i];
	for (i = 0; i < n; i++)
		ej[i] = (int *) malloc(2 * sizeof *ej[i]);
	for (h = 0; h < m; h++) {
		scanf("%d%d", &i, &j), i--, j--;
		append(i, j), append(j, i);
	}
	lower = -1, upper = INF;
	while (upper - lower > 1) {
		int t = (lower + upper) / 2;

		if (solve(t))
			upper = t;
		else
			lower = t;
	}
	printf("%d\n", upper);
	return 0;
}

Compilation message (stderr)

Main.c: In function 'append':
Main.c:46:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   46 |  if (o >= 2 && (o & o - 1) == 0)
      |                     ~~^~~
Main.c: In function 'solve':
Main.c:63:31: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   63 |   if (h2 == cnt2 || h1 < cnt1 && aa[qu1[h1]] < dd[qu2[h2]]) {
      |                     ~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.c: In function 'main':
Main.c:90:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   90 |  scanf("%d%d", &n, &m);
      |  ^~~~~~~~~~~~~~~~~~~~~
Main.c:92:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   92 |   scanf("%d", &aa[i]);
      |   ^~~~~~~~~~~~~~~~~~~
Main.c:101:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  101 |   scanf("%d%d", &i, &j), i--, j--;
      |   ^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 22 / 22
• Subtask 2: 10 / 10
• Subtask 3: 31 / 31
• Subtask 4: 37 / 37