Submission #151227

#	Time	Username	Problem	Language	Result	Execution time	Memory
151227		Bodo171	Ancient Books (IOI17_books)	C++14	50 / 100	314 ms	26776 KiB

books

#include "books.h"
#include <iostream>
using namespace std;
const int nmax=1000*1000+5;
int st[nmax],dr[nmax],viz[nmax];
int n,to_l,to_r,l,r,i,x,l1,l2,r1,r2,oldl,oldr,steps_left,steps_right;
long long abss(long long x)
{
    if(x<0) return -x;
    return x;
}
void ext(int &L,int &R,int oldL,int oldR)
{
    int nxtL,nxtR;
    while(oldL!=L||oldR!=R)
    {
        nxtL=L;nxtR=R;
        for(int it=oldL-1;it>=L;it--)
        {
            nxtL=min(nxtL,st[it]);
            nxtR=max(nxtR,dr[it]);
        }
        for(int it=oldR+1;it<=R;it++)
        {
            nxtL=min(nxtL,st[it]);
            nxtR=max(nxtR,dr[it]);
        }
        oldL=L;oldR=R;
        L=nxtL;R=nxtR;
    }
}
long long minimum_walk(vector<int> p, int s) {
    long long ans=0;
    n=p.size();
    to_l=s;to_r=s;
    for(i=0; i<p.size(); i++)
    {
        if(p[i]!=i)
        {
            to_l=min(to_l,i);
            to_r=max(to_r,i);
        }
        ans+=1LL*abss(i-p[i]);
        if(!viz[i])
        {
            st[i]=dr[i]=i;
            x=i;
            while(!viz[x])
            {
                st[i]=min(st[i],x);
                dr[i]=max(dr[i],x);
                viz[x]=1;
                x=p[x];
            }
            x=p[i];
            while(x!=i)
            {
                st[x]=st[i];
                dr[x]=dr[i];
                x=p[x];
            }
        }
    }
    l=st[s];r=dr[s];
    ext(l,r,s,s);
    while(l>to_l||r<to_r)
    {
        l1=l,r1=r;oldl=l;oldr=r;
        while(l1>to_l&&r1==r)
        {
            l1--;steps_left+=2;
            ext(l1,r1,oldl,oldr);
            oldl=l1;oldr=r1;

        }
        l2=l,r2=r;oldl=l;oldr=r;
        while(r2<to_r&&l2==l)
        {
            r2++;steps_right+=2;
            ext(l2,r2,oldl,oldr);
            oldl=l2;oldr=r2;
        }
        if(r1>r)
        {
            ans+=1LL*min(steps_left,steps_right);
            l=l1;r=r1;
        }
        else
        {
            ans+=1LL*steps_left;
            ans+=1LL*steps_right;
            l=l1;r=r2;
        }
    }
	return ans;
}

Compilation message (stderr)

books.cpp: In function 'long long int minimum_walk(std::vector<int>, int)':
books.cpp:36:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(i=0; i<p.size(); i++)
              ~^~~~~~~~~

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