Submission #373121

#	Time	Username	Problem	Language	Result	Execution time	Memory
373121		luciocf	Collecting Stamps 3 (JOI20_ho_t3)	C++14	100 / 100	115 ms	133996 KiB

ho_t3

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int maxn = 210;
const ll inf = 1e18;

int n, L;
int x[maxn], t[maxn];

ll dp[maxn][maxn][maxn][2];

int main(void)
{
	scanf("%d %d", &n, &L);

	for (int i = 1; i <= n; i++)
		scanf("%d", &x[i]);

	for (int i = 1; i <= n; i++)
		scanf("%d", &t[i]);

	for (int l = 0; l <= n; l++)
		for (int r = 0; r <= n; r++)
			for (int k = 0; k <= n; k++)
				dp[l][r][k][0] = dp[l][r][k][1] = inf;

	dp[0][0][0][0] = dp[0][0][0][1] = 0;

	x[n+1] = L;

	for (int l = 0; l <= n; l++)
	{
		for (int r = 0; r+l <= n; r++)
		{
			for (int k = 0; k <= n; k++)
			{
				ll ans = inf;

				if (l == 0 && r == 0 && k == 0) ans = 0;

				int pos_l = n-l+1;

				if (l > 0)
				{
					ll c1 = dp[l-1][r][k][0] + 1ll*x[pos_l+1] - 1ll*x[pos_l];
					ll c2 = dp[l-1][r][k][1] + 1ll*L-1ll*x[pos_l] + 1ll*x[r];

					ans = min(ans, c1);
					ans = min(ans, c2);

					if (k > 0)
					{
						c1 -= dp[l-1][r][k][0]; c1 += dp[l-1][r][k-1][0];
						c2 -= dp[l-1][r][k][1]; c2 += dp[l-1][r][k-1][1];

						if (c1 <= 1ll*t[pos_l]) ans = min(ans, c1);
						if (c2 <= 1ll*t[pos_l]) ans = min(ans, c2);
					}
				}

				dp[l][r][k][0] = ans;

				ans = inf;

				if (l == 0 && r == 0 && k == 0) ans = 0;

				if (r > 0)
				{
					ll c1 = dp[l][r-1][k][1] + 1ll*x[r] - 1ll*x[r-1];
					ll c2 = dp[l][r-1][k][0] + 1ll*L-1ll*x[pos_l] + 1ll*x[r];

					ans = min(ans, c1);
					ans = min(ans, c2);

					if (k > 0)
					{
						c1 -= dp[l][r-1][k][1]; c1 += dp[l][r-1][k-1][1];
						c2 -= dp[l][r-1][k][0]; c2 += dp[l][r-1][k-1][0];

						if (c1 <= 1ll*t[r]) ans = min(ans, c1);
						if (c2 <= 1ll*t[r]) ans = min(ans, c2);
					}
				}

				dp[l][r][k][1] = ans;
			}
		}
	}

	int ans = 0;

	for (int l = 0; l <= n; l++)
		for (int r = 0; r+l <= n; r++)
			for (int k = 0; k <= n; k++)
				if (dp[l][r][k][0] != inf || dp[l][r][k][1] != inf)
					ans = max(ans, k);

	printf("%d\n", ans);
}

Compilation message (stderr)

ho_t3.cpp: In function 'int main()':
ho_t3.cpp:17:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   17 |  scanf("%d %d", &n, &L);
      |  ~~~~~^~~~~~~~~~~~~~~~~
ho_t3.cpp:20:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   20 |   scanf("%d", &x[i]);
      |   ~~~~~^~~~~~~~~~~~~
ho_t3.cpp:23:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   23 |   scanf("%d", &t[i]);
      |   ~~~~~^~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 75 / 75