Submission #593660

#	Time	Username	Problem	Language	Result	Execution time	Memory
593660		yutabi	Ancient Books (IOI17_books)	C++14	100 / 100	132 ms	15200 KiB

books

#include "books.h"


#include <bits/stdc++.h>
using namespace std;


#define pb push_back


typedef long long ll;


long long minimum_walk(std::vector<int> p, int s)
{
	int n=p.size();

	ll ans=0;

	int start_l=0;
	int start_r=n-1;

	while(start_l<s && p[start_l]==start_l)
	{
		start_l++;
	}

	while(s<start_r && p[start_r]==start_r)
	{
		start_r--;
	}

	int mex_low=start_l;
	int mex_high=start_r;

	vector <bool> v(1000007,0);

	int left_limit=start_l;
	int right_limit=start_r;

	for(int i=start_l;i<=s;i++)
	{
		ans+=abs(i-p[i]);

		v[p[i]]=1;

		while(v[mex_low]==1)
		{
			mex_low++;
		}

		if(mex_low>i)
		{
			if(i!=s)
				ans+=2;

			left_limit=i+1;
		}
	}

	v=vector <bool> (1000007,0);

	for(int i=start_r;i>=s;i--)
	{
		ans+=abs(i-p[i]);

		v[p[i]]=1;

		while(mex_high>=0 && v[mex_high]==1)
		{
			mex_high--;
		}

		if(mex_high<i)
		{
			if(i!=s)
				ans+=2;

			right_limit=i-1;
		}
	}

	ans-=abs(s-p[s]);

	int lptr=s;
	int rptr=s;

	v=vector <bool> (1000007,0);

	mex_low=s;
	mex_high=s;

	int mini=p[s];
	int maxi=p[s];

	v[p[s]]=1;

	while(lptr>=left_limit && rptr<=right_limit)
	{
		while(mini<lptr || rptr<maxi)
		{
			while(mini<lptr)
			{
				lptr--;

				v[p[lptr]]=1;

				mini=min(mini,p[lptr]);
				maxi=max(maxi,p[lptr]);
			}

			while(rptr<maxi)
			{
				rptr++;

				v[p[rptr]]=1;

				mini=min(mini,p[rptr]);
				maxi=max(maxi,p[rptr]);
			}
		}

		while(mex_low>=0 && v[mex_low]==1)
		{
			mex_low--;
		}

		while(v[mex_high]==1)
		{
			mex_high++;
		}

		if(lptr==left_limit && rptr==right_limit)
		{
			break;
		}

		ans+=2;

		mini--;
		maxi++;
	}

	/*if(left_limit>right_limit)
	{
		ans-=2;
	}*/
	
	return ans;
}

• Subtask 1: 12 / 12
• Subtask 2: 10 / 10
• Subtask 3: 28 / 28
• Subtask 4: 20 / 20
• Subtask 5: 30 / 30