Submission #70782

#	Time	Username	Problem	Language	Result	Execution time	Memory
70782		gnoor	Ancient Books (IOI17_books)	C++17	50 / 100	314 ms	19052 KiB

books

#include "books.h"

#include <vector>
#include <algorithm>
#include <cmath>
#include <cassert>
#include <cstdio>

using namespace std;

bool visit[1000100];

vector<pair<int,int>> uni(vector<pair<int,int>> &tbl) {
	sort(tbl.begin(),tbl.end(),[](const pair<int,int> &a,const pair<int,int> &b) {
			if (a.second!=b.second) return a.second<b.second;
			return a.first<b.first;
			});
	vector<pair<int,int>> re;
	for (int i=0;i<(int)tbl.size();i++) {
		int curl=tbl[i].first;
		while (!re.empty()&&tbl[i].first<=re.back().second) {
			curl=min(curl,re.back().first);
			re.pop_back();
		}
		re.push_back({curl,tbl[i].second});
	}
	return re;
}

vector<pair<int,int>> rem(vector<pair<int,int>> &tbl,vector<pair<int,int>> &out) {
	sort(tbl.begin(),tbl.end(),[](const pair<int,int> &a,const pair<int,int> &b) {
			if (a.second!=b.second) return a.second<b.second;
			return a.first>b.first;
			});
	
	vector<pair<int,int>> re;
	for (int i=0;i<(int)tbl.size();i++) {
		while (!re.empty()&&tbl[i].first<=re.back().first) {
			out.push_back(re.back());
			re.pop_back();
		}
		re.push_back(tbl[i]);
	}
	return re;
}

long long minimum_walk(vector<int> p, int s) {
	int n=(int)p.size();
	vector<pair<int,int>> coord;
	vector<pair<int,int>> nonover;
	vector<pair<int,int>> over;
	long long ans=0;
	for (int i=0;i<n;i++) {
		if (visit[i]) continue;
		visit[i]=true;
		int mn=i;
		int mx=i;
		int cur=p[i];
		ans+=abs(p[i]-i);
		while (cur!=i) {
			visit[cur]=true;
			mx=max(mx,cur);
			mn=min(mn,cur);
			ans+=abs(p[cur]-cur);
			cur=p[cur];
		}
		if (mn==mx) continue;
		coord.push_back({mn,mx});
		if (mn<=s&&s<=mx) over.push_back({mn,mx});
		else nonover.push_back({mn,mx});
		if (mn!=mx) coord.push_back({mn,mx});
		
	}
	coord.push_back({s,s});
	auto re=uni(coord);
	for (int i=1;i<(int)re.size();i++) {
		ans+=(re[i].first-re[i-1].second)*2;
	}

	auto over2=rem(over,nonover);

	int ll=(over2.empty()?s:over2.back().first);
	int rr=(over2.empty()?s:over2.front().second);

	nonover.push_back({ll,ll});
	nonover.push_back({rr,rr});
	nonover.push_back({s,s});

	auto nonover2=uni(nonover);

	long long addr=0;
	bool stflag=false;
	for (int i=0;i<(int)nonover2.size();i++) {
		if (nonover2[i].first<=s&&s<=nonover2[i].second) {
			stflag=true;
			if (nonover2[i].first<=rr&&rr<=nonover2[i].second) break;
			continue;
		}
		if (!stflag) continue;
		addr+=(nonover2[i].first-nonover2[i-1].second)*2;	
		if (nonover2[i].first<=rr&&rr<=nonover2[i].second) break;
	}
	stflag=false;
	long long addl=0;
	for (int i=(int)nonover2.size()-1;i>=0;i--) {
		if (nonover2[i].first<=s&&s<=nonover2[i].second) {
			stflag=true;
			if (nonover2[i].first<=ll&&ll<=nonover2[i].second) break;
			continue;
		}
		if (!stflag) continue;
		addl+=(nonover2[i+1].first-nonover2[i].second)*2;	
		if (nonover2[i].first<=ll&&ll<=nonover2[i].second) break;
	}
	ans+=min(addl,addr);
		
	return ans;
}

• Subtask 1: 12 / 12
• Subtask 2: 10 / 10
• Subtask 3: 28 / 28
• Subtask 4: 0 / 20
• Subtask 5: 0 / 30