Submission #773204

#	Time	Username	Problem	Language	Result	Execution time	Memory
773204		rainboy	Alternating Heights (CCO22_day1problem1)	C11	25 / 25	427 ms	13844 KiB

Main

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

#define N	3000
#define M	3000

int *ej[N], eo[N], fo[N], 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 ii[M], m;

int check(int l, int r) {
	static int qu[N];
	int cnt, h, i, j, o;

	for (i = 0; i < n; i++)
		ej[i] = (int *) malloc(2 * sizeof *ej[i]), eo[i] = 0, fo[i] = 0;
	for (h = l; h < r; h++)
		if (h % 2 == 0)
			append(ii[h], ii[h + 1]), fo[ii[h + 1]]++;
		else
			append(ii[h + 1], ii[h]), fo[ii[h]]++;
	cnt = 0;
	for (i = 0; i < n; i++)
		if (fo[i] == 0)
			qu[cnt++] = i;
	for (h = 0; h < cnt; h++) {
		i = qu[h];
		for (o = eo[i]; o--; ) {
			j = ej[i][o];
			if (--fo[j] == 0)
				qu[cnt++] = j;
		}
	}
	for (i = 0; i < n; i++)
		free(ej[i]);
	return cnt == n;
}

int main() {
	static int rr[M];
	int q, h, l, r;

	scanf("%d%d%d", &m, &n, &q);
	for (h = 0; h < m; h++)
		scanf("%d", &ii[h]), ii[h]--;
	for (l = 0, r = 0; l < m; l++) {
		while (r < m && check(l, r))
			r++;
		rr[l] = r;
	}
	while (q--) {
		scanf("%d%d", &l, &r), l--, r--;
		printf(r < rr[l] ? "YES\n" : "NO\n");
	}
	return 0;
}

Compilation message (stderr)

Main.c: In function 'append':
Main.c:12:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   12 |  if (o >= 2 && (o & o - 1) == 0)
      |                     ~~^~~
Main.c: In function 'main':
Main.c:51:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   51 |  scanf("%d%d%d", &m, &n, &q);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.c:53:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   53 |   scanf("%d", &ii[h]), ii[h]--;
      |   ^~~~~~~~~~~~~~~~~~~
Main.c:60:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   60 |   scanf("%d%d", &l, &r), l--, r--;
      |   ^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 6 / 6
• Subtask 3: 7 / 7
• Subtask 4: 8 / 8