Submission #961044

#	Time	Username	Problem	Language	Result	Execution time	Memory
961044		MarwenElarbi	Ancient Books (IOI17_books)	C++17	70 / 100	2025 ms	21252 KiB

books

#include "books.h"
#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
using namespace std;
bool vis[1000005];
vector<int> l(1000000),r(1000000);
long long minimum_walk(std::vector<int> p, int s){
    int n=p.size();
    long long ans=0;
    int en=s;
    int bg=s;
    //cout << ans<<endl;
    vector<int> cycle;
    for (int i = 0; i < n; ++i)
    {
        ans+=abs(p[i]-i);
        int cur=i;
        if(p[cur]!=cur){
            en=max(en,cur);
            bg=min(bg,cur);
        }
        if(vis[cur]) continue;
        cycle.clear();
        int mn=1e6+5;
        int mx=-1;
        while(vis[cur]==0){
            cycle.push_back(cur);
            vis[cur]=1;
            mx=max(mx,cur);
            mn=min(mn,cur);
            cur=p[cur];
        }
        for(int u:cycle){
            //cout <<u<<" ";
            l[u]=mn;
            r[u]=mx;
        } 
    }
    //cout <<"nabba"<<endl;
    int curl=s;int ml=l[s];
    int curr=s;int mr=r[s];
    while(curr<en||curl>bg){
        //cout <<curl<<" "<<curr<<endl;
        if(curl>ml){
            curl--;
            mr=max(mr,r[curl]);
            ml=min(ml,l[curl]);
        }else if(curr<mr){
            curr++;
            mr=max(mr,r[curr]);
            ml=min(ml,l[curr]);
        }else{
            //cout <<"hey"<<endl;
            bool ok=0;
            int costl=0;
            int x=mr;
            int cl=mr;
            while(x>bg){
                cl=min(cl,l[x]);
                if(x==cl){
                    costl+=2;
                    cl--;
                }
                x--;
                if(r[x]>mr){
                    ok=true;
                    break;
                }
            }
            x=ml;
            int cr=ml;
            int costr=0;
            while(x<en){
                cr=max(cr,r[x]);
                if(x==cr){
                    cr++;
                    costr+=2;
                }
                x++;
                if(l[x]<ml){
                    ok=true;
                    break;
                }
            }
            if(ok){
                if(costl>costr){
                    mr=cr;
                    ans+=costr;
                }else{
                    ml=cl;
                    ans+=costl;
                }
            }else{
                ans+=costl+costr;
                break;
            }
        }
    }
    return ans;
}

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