Submission #392854

#	Time	Username	Problem	Language	Result	Execution time	Memory
392854		faresbasbs	Ancient Books (IOI17_books)	C++14	100 / 100	206 ms	42232 KiB

books

#include <bits/stdc++.h>
#include "books.h"
using namespace std;
long long n,ans,mini,maxi,num,cyc[1000001],L[1000001],R[1000001];
bool seen[1000001];
vector<int> p;

void dfs(long long curr){
	seen[curr] = 1 , L[num] = min(L[num],curr) , R[num] = max(R[num],curr) , cyc[curr] = num;
	mini = min(mini,curr) , maxi = max(maxi,curr);
	if(!seen[p[curr]]){
		dfs(p[curr]);
	}
}

void extend(long long &l , long long &r){
	long long ll = min({l,L[cyc[l]],L[cyc[r]]}) , rr = max({r,R[cyc[l]],R[cyc[r]]});
	while(ll < l || r < rr){
		if(ll < l){
			l -= 1;
			ll = min(ll,L[cyc[l]]);
			rr = max(rr,R[cyc[l]]);
		}else{
			r += 1;
			ll = min(ll,L[cyc[r]]);
			rr = max(rr,R[cyc[r]]);
		}
	}
}

long long getans(long long l , long long r){
	long long ret = 0;
	while(l > mini || r < maxi){
		extend(l,r);
		bool nxtl = false;
		long long costl = 0 , ll = l ,rl = r;
		while(true){
			if(ll <= mini){
				break;
			}
			ll -= 1;
			costl += 2;
			extend(ll,rl);
			if(rl > r){
				nxtl = true;
				break;
			}
		}
		bool nxtr = false;
		long long costr = 0 , lr = l , rr = r;
		while(true){
			if(rr >= maxi){
				break;
			}
			rr += 1;
			costr += 2;
			extend(lr,rr);
			if(lr < l){
				nxtr = true;
				break;
			}
		}
		if(nxtl && nxtr){
			ret += min(costl,costr);
		}else{
			ret += costl+costr;
		}
		l = min(ll,lr) , r = max(rl,rr);
	}
	return ret;
}

long long minimum_walk(vector<int> P , int s){
	p = P , n = p.size() , mini = maxi = s;
	for(long long i = 0 ; i < n ; i += 1){
		ans += abs(p[i]-i);
		if(seen[i]){
			continue;
		}
		L[num] = R[num] = i , cyc[i] = num;
		if(i != p[i]){
			dfs(i);
		}
		num += 1;
	}
	return ans+getans(s,s);
}

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