Submission #622507

#	Time	Username	Problem	Language	Result	Execution time	Memory
622507		dozer	Tortoise (CEOI21_tortoise)	C++14	48 / 100	259 ms	398684 KiB

tortoise

#include <bits/stdc++.h>
using namespace std;
#define sp " "
#define endl "\n"
#define fastio() cin.tie(0), ios_base::sync_with_stdio(0)
#define pb push_back
#define fileio() freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout)
#define pii pair<int, int>
#define st first
#define nd second
#define N 5005
#define modulo 1000000007
#define int long long

int dp[N][N];
vector<int> pg;
int arr[N], n;

int f(int time, int ind)
{
	if (time > 2 * (n - 1) || ind > n) return 0;
	if (arr[ind] == -1) return dp[time][ind] = f(time + 1, ind + 1);
	if (dp[time][ind] != -1) return dp[time][ind];
	auto it = lower_bound(pg.begin(), pg.end(), ind);
	int nxt = modulo, prv = - modulo;
	if (it != pg.end()) nxt = *it;
	if (it != pg.begin())
	{
		it--;
		prv = *it;
	}
	int dist = min(ind - prv, nxt - ind);
	int tmp = time, inc = 0, ans = 0;
	while(tmp <= ind * 2 - 2 && inc < arr[ind])
	{
		if (nxt <= n)
		{
			for (int i = ind + 1; i <= nxt; i++)//for the last candy we buy, we can go to the next pg and come back to a forward shop
			{
				ans = max(ans, f(tmp + nxt - ind + nxt - i, i) + inc + 1);
			}
		}
		
		ans = max(ans, f(tmp + 1, ind + 1) + inc); // we can just continue to the next place without buying more candies
		ans = max(ans, inc + 1);//buy it and finish the process
		tmp += 2 * dist;
		inc++;
	}
	ans = max(ans, f(tmp + 1, ind + 1) + inc);
	ans = max(ans, f(time + 1, ind + 1));
	//cout<<time<<sp<<ind<<sp<<ans<<endl;
	return dp[time][ind] = ans;
}

int32_t main()
{
	fastio();
	memset(dp, -1, sizeof(dp));

	cin>>n;
	int sum = 0;
	for (int i = 1; i <= n; i++)
	{
		cin>>arr[i];
		if (arr[i] == -1) pg.pb(i);
		else sum += arr[i];
	}

	cout<<sum - f(0, 1)<<endl;
	cerr<<"time taken: "<<(float)clock() / CLOCKS_PER_SEC<<" seconds\n";
}

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