Submission #544760

#	Time	Username	Problem	Language	Result	Execution time	Memory
544760		rainboy	The short shank; Redemption (BOI21_prison)	C11	100 / 100	566 ms	219752 KiB

prison

/* upsolve after reading spoiler */
#include <stdio.h>
#include <stdlib.h>

#define N	2000000

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

void append(int **ej, int *eo, 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 main() {
	static int *ej[N], eo[N], *fj[N], fo[N];
	static int aa[N], qu[N], pp[N], dd[N], jj[N];
	static char passive[N];
	int n, k, t, i, j, d, o, cnt, ans;

	scanf("%d%d%d", &n, &k, &t);
	for (i = 0, j = -1; i < n; i++) {
		scanf("%d", &aa[i]);
		j = max(j, i + t - aa[i]);
		if (aa[i] > t && j >= i)
			passive[i] = 1;
	}
	cnt = 0, ans = n;
	for (i = n - 1; i >= 0; i--)
		if (passive[i]) {
			pp[i] = cnt == 0 ? -1 : qu[cnt - 1];
			qu[cnt++] = i;
		} else {
			pp[i] = -2;
			if (aa[i] > t)
				ans--;
			else
				while (cnt && qu[cnt - 1] <= i + t - aa[i])
					cnt--;
		}
	for (i = 0; i < n; i++)
		ej[i] = (int *) malloc(2 * sizeof *ej[i]);
	for (i = 0; i < n; i++)
		if (pp[i] >= 0)
			append(ej, eo, pp[i], i);
	for (i = 0; i < n; i++)
		for (o = eo[i]; o--; ) {
			j = ej[i][o];
			if (dd[i] < dd[j] + 1)
				dd[i] = dd[j] + 1, jj[i] = j;
		}
	for (i = 0; i < n; i++)
		fj[i] = (int *) malloc(2 * sizeof *fj[i]);
	for (i = 0; i < n; i++)
		if (pp[i] == -1)
			append(fj, fo, dd[i], i);
	d = n - 1;
	while (k--) {
		while (d >= 0 && fo[d] == 0)
			d--;
		if (d < 0)
			break;
		i = fj[d][--fo[d]], ans -= d + 1;
		while (dd[i] > 0) {
			for (o = eo[i]; o--; ) {
				j = ej[i][o];
				if (j != jj[i])
					append(fj, fo, dd[j], j);
			}
			i = jj[i];
		}
	}
	printf("%d\n", ans);
	return 0;
}

Compilation message (stderr)

prison.c: In function 'append':
prison.c:12:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   12 |  if (o >= 2 && (o & o - 1) == 0)
      |                     ~~^~~
prison.c: In function 'main':
prison.c:23:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   23 |  scanf("%d%d%d", &n, &k, &t);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~
prison.c:25:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   25 |   scanf("%d", &aa[i]);
      |   ^~~~~~~~~~~~~~~~~~~

• Subtask 1: 15 / 15
• Subtask 2: 10 / 10
• Subtask 3: 20 / 20
• Subtask 4: 10 / 10
• Subtask 5: 25 / 25
• Subtask 6: 20 / 20