Submission #1201291

#	Time	Username	Problem	Language	Result	Execution time	Memory
1201291		Zbyszek99	Ancient Books (IOI17_books)	C++20	100 / 100	788 ms	121552 KiB

books

#include "books.h"
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define ld long double
#define ull unsigned long long
#define ff first
#define ss second
#define pii pair<int,int>
#define pll pair<long long, long long>
#define vi vector<int>
#define vl vector<long long>
#define pb push_back
#define rep(i, b) for(int i = 0; i < (b); ++i)
#define rep2(i,a,b) for(int i = a; i <= (b); ++i)
#define rep3(i,a,b,c) for(int i = a; i <= (b); i+=c)
#define count_bits(x) __builtin_popcountll((x))
#define all(x) (x).begin(),(x).end()
#define siz(x) (int)(x).size()
#define forall(it,x) for(auto& it:(x))
using namespace __gnu_pbds;
using namespace std;
typedef tree<int, null_type, less<int>, rb_tree_tag,tree_order_statistics_node_update> ordered_set;
mt19937 mt;void random_start(){mt.seed(chrono::time_point_cast<chrono::milliseconds>(chrono::high_resolution_clock::now()).time_since_epoch().count());}
ll los(ll a, ll b) {return a + (mt() % (b-a+1));}
const int INF = 1e9+50;
const ll INF_L = 1e18+40;
const ll MOD = 1e9+7;

bool odw[1'000'001];
int seg_ind[1'000'001];
vector<pii> segs;
int used_poz[1'000'001];

int rep_[1'000'001];
int min_c[1'000'001];
int max_c[1'000'001];
bool top_seg[1'000'001];

int fint(int v)
{
	if(rep_[v] == v) return v;
	rep_[v] = fint(rep_[v]);
	return rep_[v];
}

void onion(int a, int b)
{
	a = fint(a);
	b = fint(b);
	max_c[b] = max(max_c[a],max_c[b]);
	min_c[b] = min(min_c[a],min_c[b]); 
	rep_[a] = b;
}

ll minimum_walk(vi p, int s) 
{
	int n = siz(p);
	ll ans = -2;
	rep(i,n)
	{
		if(odw[i] == 0)
		{
			int cur = i;
			vi ls;
			while(odw[cur] == 0)
			{
				ls.pb(cur);
				odw[cur] = 1;
				ans += abs(cur-p[cur]);
				cur = p[cur];
			}
			int min_ = 1e9;
			int max_ = -1e9;
			forall(it,ls)
			{
				min_ = min(min_,it);
				max_ = max(max_,it);
			}
			segs.pb({min_,max_});
			forall(it,ls)
			{
				seg_ind[it] = siz(segs)-1;
			}
		}
	}
	if(ans == -2) return 0;
	rep(i,siz(segs))
	{
		rep_[i] = i;
		min_c[i] = segs[i].ff;
		max_c[i] = segs[i].ss;
	}
	vector<pii> sort_segs;
	rep(i,siz(segs))
	{
		sort_segs.pb({segs[i].ss,i});
	}
	sort(all(sort_segs));
	set<pii> segs_set;
	forall(it,sort_segs)
	{
		int l = segs[it.ss].ff;
		int r = segs[it.ss].ss;
		while(true)
		{
			auto it2 = segs_set.lower_bound({l,-1e9});
			if(it2 == segs_set.end()) break;
			onion(it.ss,(*it2).ss);
			segs_set.erase(it2);
		}
		segs_set.insert({max_c[fint(it.ss)],it.ss});
	}
	vector<pair<int,pii>> se;
	rep(i,siz(segs))
	{
		if(fint(i) == i)
		{
			se.pb({max_c[fint(i)] - min_c[fint(i)],{min_c[fint(i)],i}});
		}
	}
	sort(all(se));
	reverse(all(se));
	forall(it,se)
	{
		if(used_poz[it.ss.ff] == 0)
		{
			top_seg[it.ss.ff] = 1;
			ans+=2;
			rep2(i,it.ss.ff,it.ss.ff+it.ff)
			{
				used_poz[i] = 1;
			}
		}
	}
	int pref = 0;
	int suf = 0;
	rep(i,n)
	{
		if(p[i] == i) pref++;
		else break;
	}
	for(int i = n-1; i >= 0; i--)
	{
		if(p[i] == i) suf++;
		else break;
	}
	if(s < pref)
	{
		return ans - suf*2 - pref*2 + (pref-s)*2;
	}
	if(s >= n-suf)
	{
		return ans - suf*2 - pref*2 + (n-suf-s+1)*2;
	}
	ans -= suf*2 + pref*2;
	int min_dist = 1e9;
	priority_queue<pii,vector<pii>,greater<pii>> pq;
	pq.push({0,s});
	rep(i,n) odw[i] = 0;
	set<int> un_dist;
	rep(i,n) un_dist.insert(i);
	while(!pq.empty())
	{
		pii t = pq.top();
		pq.pop();
		if(odw[t.ss]) continue;
		odw[t.ss] = 1;
		if(un_dist.find(t.ss) != un_dist.end())
		{
			un_dist.erase(un_dist.find(t.ss));
		}
		if(top_seg[t.ss]) min_dist = min(min_dist,t.ff);
		int l = segs[seg_ind[t.ss]].ff;
		int r = segs[seg_ind[t.ss]].ss;
		while(true)
		{
			auto it = un_dist.lower_bound(l);
			if(it == un_dist.end()) break;
			if((*it) > r) break;
			pq.push({t.ff,(*it)});
			un_dist.erase(it);
		}
		if(t.ss != 0) pq.push({t.ff+1,t.ss-1});
		if(t.ss != n-1) pq.push({t.ff+1,t.ss+1});
	}
	return ans + min_dist*2;
}

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