Submission #561026

#	Time	Username	Problem	Language	Result	Execution time	Memory
561026		neki	Ancient Books (IOI17_books)	C++14	50 / 100	208 ms	48660 KiB

books

#include <bits/stdc++.h>
#define ll long long
#define vc vector
#define all(a) a.begin(), a.end()
#define fi first
#define se second
using namespace std;
 
ll minimum_walk(vc<int> p, int s){
    ll n=p.size();
    ll ans=0;
    
    vc<ll> doseg(n);iota(all(doseg), 0);
    
    vc<ll> vis(n, 0);
    for(ll i=0;i<n;++i) if(!vis[i]){
        vc<ll> cyc;
        for(ll cur=i;1;){
            vis[cur]=1;
            cyc.push_back(cur);
            ll nex=p[cur];
            ans+=abs(nex-cur);
            if(nex==i)break;
            cur=nex;
        }
        
        ll zac=(*min_element(all(cyc))), konc=(*max_element(all(cyc)));
        doseg[konc]=min(doseg[konc], zac);
    }
    vc<pair<ll, ll>> ints;
    for(ll i=0;i<n;++i){
        while(ints.size() and doseg[i]<=ints.back().second) ints.pop_back();
        if(ints.size()==0) ints.emplace_back((ll)0, i);
        else ints.emplace_back(ints.back().second+1, i);
    }
    ll st;for(ll i=0;i<ints.size();++i) if(ints[i].fi<=s and s<=ints[i].se) st=i;
    ll fl=st;for(ll i=st-1;i>=0;--i) if(ints[i].fi!=ints[i].se) fl=i;
    ll fr=st;for(ll i=st+1;i<ints.size();++i) if(ints[i].fi!=ints[i].se) fr=i;
    ans+=2 * (fr-fl);
    return ans;
}

Compilation message (stderr)

books.cpp: In function 'long long int minimum_walk(std::vector<int>, int)':
books.cpp:36:23: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   36 |     ll st;for(ll i=0;i<ints.size();++i) if(ints[i].fi<=s and s<=ints[i].se) st=i;
      |                      ~^~~~~~~~~~~~
books.cpp:38:29: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   38 |     ll fr=st;for(ll i=st+1;i<ints.size();++i) if(ints[i].fi!=ints[i].se) fr=i;
      |                            ~^~~~~~~~~~~~
books.cpp:37:21: warning: 'st' may be used uninitialized in this function [-Wmaybe-uninitialized]
   37 |     ll fl=st;for(ll i=st-1;i>=0;--i) if(ints[i].fi!=ints[i].se) fl=i;
      |                     ^

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