Submission #500639

#	Time	Username	Problem	Language	Result	Execution time	Memory
500639		rainboy	Tortoise (CEOI21_tortoise)	C11	0 / 100	1 ms	344 KiB

tortoise

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

#define N	5000
#define INF	0x3f3f3f3f

int abs_(int a) { return a > 0 ? a : -a; }
int min(int a, int b) { return a < b ? a : b; }
int max(int a, int b) { return a > b ? a : b; }

int main() {
	static int aa[N], ll[N], rr[N], tt[N], dp[N][N * 2 + 1], dq[N][N * 2 + 1];
	int n, i, j, k, k_;
	long long ans;

	scanf("%d", &n);
	for (i = 0; i < n; i++)
		scanf("%d", &aa[i]);
	for (i = 0; i < n; i++)
		if (aa[i] != -1) {
			for (j = i - 1; j >= 0; j--)
				if (aa[j] == -1)
					break;
			ll[i] = j;
			for (j = i + 1; j < n; j++)
				if (aa[j] == -1)
					break;
			rr[i] = j;
			tt[i] = min(ll[i] == -1 ? INF : i - ll[i], rr[i] == n ? INF : rr[i] - i) * 2;
		}
	for (i = 0; i < n; i++) {
		memset(dp[i], 0x3f, (n * 2 + 1) * sizeof *dp[i]);
		memset(dq[i], 0x3f, (n * 2 + 1) * sizeof *dq[i]);
	}
	ans = 0;
	for (i = 0; i < n; i++)
		if (aa[i] > 0) {
			for (k = 0; k <= n * 2; k++) {
				if ((j = ll[i]) >= 0)
					dp[i][k] = min(dp[i][k], dq[j][k] + i - j);
				if ((j = rr[i]) < n)
					dp[i][k] = min(dp[i][k], dq[j][k] + j - i);
			}
			dp[i][1] = min(dp[i][1], i);
			for (k = n * 2; k >= 0; k--) {
				int t = dp[i][k];

				if (t > i * 2)
					continue;
				for (k_ = k + 1; k_ <= n * 2 && k_ - k < aa[i]; k_++)
					dp[i][k_] = min(dp[i][k_], t + tt[i] * (k_ - k));
			}
			for (k = 0; k <= n * 2; k++) {
				int t = dp[i][k];

				if (t > i * 2)
					continue;
				ans = max(ans, k);
				if (k < n * 2) {
					if ((j = ll[i]) >= 0)
						dq[j][k + 1] = min(dp[j][k + 1], t + i - j);
					if ((j = rr[i]) < n)
						dq[j][k + 1] = min(dp[j][k + 1], t + j - i);
				}
			}
		}
	ans = -ans;
	for (i = 0; i < n; i++)
		if (aa[i] > 0)
			ans += aa[i];
	printf("%lld\n", ans);
	return 0;
}

Compilation message (stderr)

tortoise.c: In function 'main':
tortoise.c:16:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   16 |  scanf("%d", &n);
      |  ^~~~~~~~~~~~~~~
tortoise.c:18:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   18 |   scanf("%d", &aa[i]);
      |   ^~~~~~~~~~~~~~~~~~~

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