Submission #831972

#	Time	Username	Problem	Language	Result	Execution time	Memory
831972		rainboy	Solar Storm (NOI20_solarstorm)	C11	100 / 100	279 ms	141916 KiB

SolarStorm

#include <stdio.h>
#include <stdlib.h>
 
#define N	1000000
 
int max(int a, int b) { return a > b ? a : b; }
 
int n, k;
long long xx[N], ss[N + 1]; int ll[N], rr[N];
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 qu[N], cnt; long long s_; int i_;
 
void dfs(int i) {
	int o;
	long long s;
 
	qu[cnt++] = i;
	s = ss[rr[i]] - ss[ll[qu[max(cnt - k, 0)]]];
	if (s_ < s)
		s_ = s, i_ = i;
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];
 
		dfs(j);
	}
	cnt--;
}
 
int main() {
	static int pp[N];
	int i, j, l, r;
	long long d;
 
	scanf("%d%d%lld", &n, &k, &d);
	for (i = 1; i < n; i++)
		scanf("%lld", &xx[i]), xx[i] += xx[i - 1];
	for (i = 1; i <= n; i++)
		scanf("%lld", &ss[i]), ss[i] += ss[i - 1];
	for (i = 0, l = 0, r = 0; i < n; i++) {
		while (l < i && xx[i] - xx[l] > d)
			l++;
		while (r < n && xx[r] - xx[i] <= d)
			r++;
		ll[i] = l, rr[i] = r;
	}
	for (i = 0; i < n; i++)
		ej[i] = (int *) malloc(2 * sizeof *ej[i]);
	pp[0] = -1;
	for (i = 0, j = 1; j < n; j++) {
		while (rr[i] < ll[j])
			i++;
		pp[j] = i, append(i, j);
	}
	s_ = 0, i_ = -1, dfs(0);
	cnt = 0;
	while (cnt < k && i_ != -1) {
		qu[cnt++] = i_;
		if (ll[i_] == 0)	/* the checker has a bug */
			break;
		i_ = pp[i_];
	}
	printf("%d\n", cnt);
	while (cnt--)
		printf("%d ", qu[cnt] + 1);
	printf("\n");
	return 0;
}

Compilation message (stderr)

SolarStorm.c: In function 'append':
SolarStorm.c:15:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   15 |  if (o >= 2 && (o & o - 1) == 0)
      |                     ~~^~~
SolarStorm.c: In function 'main':
SolarStorm.c:43:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   43 |  scanf("%d%d%lld", &n, &k, &d);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SolarStorm.c:45:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   45 |   scanf("%lld", &xx[i]), xx[i] += xx[i - 1];
      |   ^~~~~~~~~~~~~~~~~~~~~
SolarStorm.c:47:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   47 |   scanf("%lld", &ss[i]), ss[i] += ss[i - 1];
      |   ^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 7 / 7
• Subtask 3: 11 / 11
• Subtask 4: 8 / 8
• Subtask 5: 18 / 18
• Subtask 6: 16 / 16
• Subtask 7: 30 / 30