Submission #500708

#	Time	Username	Problem	Language	Result	Execution time	Memory
500708		rainboy	Tortoise (CEOI21_tortoise)	C11	48 / 100	3065 ms	332 KiB

tortoise

#include <stdio.h>
#include <assert.h>

#define N	5000
#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; }

void is_it_convex(int *dp, int n) {
	int i;

	for (i = 1; i < n && dp[i + 1] != -INF; i++)
		assert(dp[i - 1] - dp[i] <= dp[i] - dp[i + 1]);
}

int main() {
	static int aa[N], dp[N * 2 + 1];
	int n, h, i, j, k, r, ans;

	scanf("%d", &n);
	for (i = 0; i < n; i++)
		scanf("%d", &aa[i]);
	for (k = 0; k <= n * 2; k++)
		dp[k] = -INF;
	dp[0] = 0;
	for (i = -1, j = 0; j <= n; j++)
		if (j == n || aa[j] == -1) {
			int d_, h_, i_, j_;

			d_ = -1, h_ = -1;
			for (h = i + 1; h <= j; h++)
				if (aa[h] > 0) {
					int d;

					d = INF;
					if (i != -1)
						d = min(d, h - i);
					if (j != n)
						d = min(d, j - h);
					if (d_ < d)
						d_ = d, h_ = h;
				}
			i_ = max(i, 0), j_ = min(j, n - 1);
			if (d_ == -1) {
				for (k = 0; k <= n * 2; k++)
					if (dp[k] != -INF)
						dp[k] += j_ - i_;
			} else {
				for (h = i + 1; h < h_; h++)
					for (r = 0; r < aa[h]; r++)
						for (k = n * 2; k >= 0; k--)
							if (dp[k] != -INF && dp[k] + h - i >= 0)
								dp[k + 1] = max(dp[k + 1], dp[k] - (h - i) * 2);
				is_it_convex(dp, n * 2 + 1);
				if (j == n || i >= 0 && h_ - i <= j - h_) {
					for (r = 0; r < aa[h_] - 1; r++)
						for (k = n * 2; k >= 0; k--)
							if (dp[k] != -INF && dp[k] + h_ - i >= 0)
								dp[k + 1] = max(dp[k + 1], dp[k] - (h_ - i) * 2);
					is_it_convex(dp, n * 2 + 1);
					for (k = n * 2; k >= 0; k--)
						if (dp[k] != -INF) {
							if (dp[k] + h_ - i_ >= 0)
								dp[k + 1] = max(dp[k + 1], dp[k] + j_ - i_);
							dp[k] += j_ - i_;
						}
					is_it_convex(dp, n * 2 + 1);
				} else {
					for (k = n * 2; k >= 0; k--)
						if (dp[k] != -INF) {
							if (dp[k] + h_ - i_ >= 0)
								dp[k + 1] = max(dp[k + 1], dp[k] + j_ - i_);
							dp[k] += j_ - i_;
						}
					is_it_convex(dp, n * 2 + 1);
					for (r = 0; r < aa[h_] - 1; r++)
						for (k = n * 2; k >= 0; k--)
							if (dp[k] != -INF && dp[k] - (j - h_) * 3 >= 0)
								dp[k + 1] = max(dp[k + 1], dp[k] - (j - h_) * 2);
					is_it_convex(dp, n * 2 + 1);
				}
				for (h = h_ + 1; h < j; h++)
					for (r = 0; r < aa[h]; r++)
						for (k = n * 2; k >= 0; k--)
							if (dp[k] != -INF && dp[k] - (j - h) * 3 >= 0)
								dp[k + 1] = max(dp[k + 1], dp[k] - (j - h) * 2);
				is_it_convex(dp, n * 2 + 1);
			}
			is_it_convex(dp, n * 2 + 1);
			i = j;
		}
	ans = 0;
	for (i = 0; i < n; i++)
		if (aa[i] > 0)
			ans += aa[i];
	k = 0;
	while (k < n * 2 && dp[k + 1] != -INF)
		k++;
	ans -= k;
	printf("%d\n", ans);
	return 0;
}

Compilation message (stderr)

tortoise.c: In function 'main':
tortoise.c:56:26: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   56 |     if (j == n || i >= 0 && h_ - i <= j - h_) {
      |                   ~~~~~~~^~~~~~~~~~~~~~~~~~~
tortoise.c:21:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   21 |  scanf("%d", &n);
      |  ^~~~~~~~~~~~~~~
tortoise.c:23:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   23 |   scanf("%d", &aa[i]);
      |   ^~~~~~~~~~~~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 10 / 10
• Subtask 3: 30 / 30
• Subtask 4: 0 / 25
• Subtask 5: 0 / 27