Submission #871463

#	Time	Username	Problem	Language	Result	Execution time	Memory
871463		Cyber_Wolf	The short shank; Redemption (BOI21_prison)	C++17	0 / 100	341 ms	21832 KiB

prison

#include <bits/stdc++.h>

using namespace std;

#define lg long long 
#define fastio ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);

const lg N = 5e5+5;

lg n, d, tim;
lg dp[2][N], p[N];
lg t[N], lst[N];
vector<lg> o;

lg C(lg i, lg j)
{
	lg ans = (j-i+1)-(n-j-(o.size()-(lower_bound(o.begin(), o.end(), j+1)-o.begin())));
	return ans;
}

//b = exclude suffix j
//c = size of suffix j
//j-i+1-(c-b)

void compute(lg lev, lg l, lg r, lg optl, lg optr)
{
	if(l > r)	return;
	lg mid = (l+r)/2;
	array<lg, 2> best = {1000000000000, optl};
	for(int i = optl; i <= min(optr, mid-1); i++)
	{
		best = min(best, {dp[(lev+1)&1][i]+C(i+1, mid), i});
	}
	dp[lev&1][mid] = best[0];
	compute(lev, l, mid-1, optl, best[1]);
	compute(lev, mid+1, r, best[1], optr);
	return;
}

int main()
{
	fastio;
	cin >> n >> d >> tim;
	for(int i = 1; i <= n; i++)	
	{
		cin >> t[i];
	}
	for(int i = 1; i <= n; i++)
	{ 
		for(int j = i; j >= 1; j--)
		{
			if(t[j]+i-j <= tim)
			{
				lst[i] = j;
				break;
			}
		}
		o.push_back(lst[i]);
	}
	sort(o.begin(), o.end());
	// for(int i = 1; i <= n; i++)
	// {
		// for(int j = 1; j <= n; j++)
		// {
			// if( j < i)	cout << "0 ";
			// else	cout << C(i, j) << ' ';		
		// }
		// cout << '\n';
	// }
	d = min(n, d);
	t[0] = 1e18;
	memset(dp, 0x3f, sizeof(dp));
	dp[d&1][0] = 0;
	for(int i = 1; i <= n; i++)	dp[d&1][i] = C(1, i);
	for(int i = d-1; i >= 0; i--)
	{
		for(int j = 1; j <= n; j++)	dp[i&1][j] = 1e15;
		compute(i, 1, n, 1, n);
	}
	cout << dp[0][n] << '\n';
}

• Subtask 1: 0 / 15
• Subtask 2: 0 / 10
• Subtask 3: 0 / 20
• Subtask 4: 0 / 10
• Subtask 5: 0 / 25
• Subtask 6: 0 / 20