Submission #345626

#	Time	Username	Problem	Language	Result	Execution time	Memory
345626		Nursik	Feast (NOI19_feast)	C++14	51 / 100	43 ms	22252 KiB

feast

#include <bits/stdc++.h>

#define f first
#define s second
#define ll long long
#define pb push_back
#define all(v) v.begin(),v.end() 
#define ld long double

using namespace std; 
 
void data() {
	#ifdef NURS
        freopen("main.in", "r", stdin);
        freopen("main.out", "w", stdout);
    #endif	
} 
void win()
{	
	ios_base::sync_with_stdio(0),
	cin.tie(0),cout.tie(0);
}

int block = 400;
const ld eps = 1e-6; 

const int N = 1e6 + 500;
const int mod = 1e9 + 7;

const ll hh = 100010683;
const ll hh2 = 150005819;

int n, k, g, pos;
ll a[N];
ll s, ans;
ll dp[5000][5000], dp2[5000][5000], pref[5000];
int main()
{
	data();              
	win();        
	cin >> n >> k;
	bool was = 0;
	for (int i = 1; i <= n; i++)
	{
		cin >> a[i];
		was = was | (a[i] < 0), s += a[i];
		if (a[i] < 0)
			g++, pos = i;
		pref[i] += pref[i - 1] + a[i];
	}
	//first subtask
	if (was == 0)
	{
		cout << s << '\n';
		return 0;
	}
	//second subtask
	if (g == 1 && k >= 2)
	{
		cout << s - a[pos] << '\n';
		return 0;	
	}
	else if (g == 1 && k == 1)
	{
		ans = max(ans, s);
		s = 0;
		for (int i = 1; i < pos; i++)
			s += a[i];
		ans = max(ans, s), s = 0;
		for (int i = pos + 1; i <= n; i++)
			s += a[i];
		ans = max(ans, s);
		cout << ans << '\n';
		return 0;
	}
	//3 subtask
	ll mn = 0;
	for (int i = 1; i <= n; i++)
	{
		ans = max(ans, pref[i] - mn);
		if (i == 1)
			mn = pref[i];
		else
			mn = min(mn, pref[i]);	
	}
	if (k == 1)
	{
		cout << ans;
		return 0;
	}
	//4, 5 subtasks
	if (n <= 300)
	{
		for (int i = 0; i <= n; i++)
		{
			for (int j = 0; j <= k; j++)
			{
				dp[i][j] = -1e9;
			} 
		}
		dp[0][0] = 0;
		for (int i = 1; i <= n; i++)
		{
			for (int j = 1; j <= k; j++)
			{
				for (int len = 0; len <= i; len++)
				{
					if (dp[i - len][j - 1] != -1e9)
					{
						dp[i][j] = max(dp[i - len][j - 1] + pref[i] - pref[i - len], dp[i][j]); 
					}
				}
				dp[i][j] = max(dp[i][j], dp[i - 1][j]);
				if (i == n && j == k)
					ans = max(ans, dp[i][j]);
			}
			dp[i][0] = max(dp[i][0], dp[i - 1][0]);
		}
		cout << ans;
	}
	else
	{
		for (int i = 0; i <= n; i++)
		{
			for (int j = 0; j <= k; j++)
			{
				dp[i][j] = -1e9, dp2[i][j] = -1e9;;
			} 
		}
		dp[0][0] = 0, dp2[0][0] = 0;
		for (int i = 1; i <= n; i++)
		{
			for (int j = 1; j <= k; j++)
			{
				dp[i][j] = max(dp[i][j], dp[i - 1][j] + a[i]);
				dp[i][j] = max(dp[i][j], dp2[i - 1][j - 1] + a[i]);
				dp2[i][j] = max(dp2[i - 1][j], dp2[i][j]);
				dp2[i][j] = max(dp2[i][j], dp[i][j]);
				ans = max(ans, dp2[i][j]);
				ans = max(ans, dp[i][j]);
			}
		}
		cout << ans;	
	}
}

• Subtask 1: 4 / 4
• Subtask 2: 8 / 8
• Subtask 3: 18 / 18
• Subtask 4: 10 / 10
• Subtask 5: 11 / 11
• Subtask 6: 0 / 20
• Subtask 7: 0 / 29