Submission #826922

#	Time	Username	Problem	Language	Result	Execution time	Memory
826922		vnm06	Ancient Books (IOI17_books)	C++14	50 / 100	103 ms	35380 KiB

books

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

int n;
bool used[1000005];
int a[1000005];
long long ans=0;
int bri=0, Le, Ri;
pair<int, int> pr[1000005];

void dfs(int i)
{
    while(1)
    {
        used[i]=1;
        long long st=a[i]-i;
        if(st<0) st=-st;
        ans+=st;
        if(a[i]==Le) break;
        ///cout<<i<<" "<<ans<<endl;
        i=a[i];
        if(i>Ri) Ri=i;
    }
}

int tbr=0;
int rm[1000005][2];

long long minimum_walk(std::vector<int> p, int s)
{
    n=p.size();
    for(int i=0; i<n; i++) a[i]=p[i];
    for(int i=0; i<n; i++)
    {
        if(!used[i])
        {
            Le=Ri=i;
            dfs(i);
            pr[bri]={Le, Ri};
            bri++;
        }
    }
    ///cout<<ans<<endl;
    sort(pr, pr+bri);
    rm[0][0]=pr[0].first;
    rm[0][1]=pr[0].second;
    tbr=1;
    for(int i=1; i<bri; i++)
    {
        if(pr[i].first>rm[tbr-1][1])
        {
            rm[tbr][0]=pr[i].first;
            rm[tbr][1]=pr[i].second;
            tbr++;
        }
        else if(pr[i].second>=rm[tbr-1][1]) rm[tbr-1][1]=pr[i].second;
    }
    ans+=2*(tbr-1);
    for(int i=0; i<tbr; i++)
    {
        if(s<=rm[i][1]) break;
        if(rm[i][0]!=rm[i][1]) break;
        ans-=2;
    }
    for(int i=tbr-1; i>=0; i--)
    {
        if(s>=rm[i][0]) break;
        if(rm[i][0]!=rm[i][1]) break;
        ans-=2;
    }
	return ans;
}

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