Submission #983273

#	Time	Username	Problem	Language	Result	Execution time	Memory
983273		Faisal_Saqib	Permutation (APIO22_perm)	C++17	97 / 100	904 ms	684 KiB

perm

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define vll vector<ll>
vector<int> cp(ll k)// O(lg n)
{
    vector<int> ans;
    ll n_req=0;
    ll hb=-1;
    for(int j=59;j>=0;j--)
    {
        ll pw=(1ll<<j);
        if(k&pw)
        {
            if(hb==-1)
            {
                n_req+=j;
                hb=j;
            }
            else
                n_req++;
        }
    }
    ll last=n_req-1;
    int first=0;
    // cout<<last<<endl;
    for(int l=0;l<60 and l<hb;l++)
    {
        if(k&(1ll<<l))
        {
            ans.push_back(first);
            first++;
        }
        if(first<=last)
        {
            ans.push_back(last);
            last--;
        }
    }
    reverse(begin(ans),end(ans));
    return ans;
}
ll task(ll n) // O(lg n)
{
    ll cp=0;
    for(int bit=59;bit>=0;bit--)
    {
        if(n&(1ll<<bit))
        {
            cp+=bit;
            n^=(1ll<<bit);
            break;
        }
    }
    while(n)
    {
        cp++;
        n-=(n&-n);
    }
    return cp;
}
vector<int> construct_permutation(ll k)
{
    vector<int> ans=cp(k);
    ll mx=ans.size();
    if(mx<95)
    {
        return ans;
    }
    ll SQ=1e6;
    SQ=min(SQ,k);
    for(ll d=1;d<=SQ;d++)
    {
        if(k%d==0)
        {
            ll f=task(d);
            ll s=task(k/d);
            if((f+s)<mx)
            {
                mx=f+s;
                vector<int> f_=cp(d);
                vector<int> s_=cp(k/d);
                ll nm=s_.size();
                for(int i=0;i<f_.size();i++)
                    f_[i]+=nm;
                ans.clear();
                for(auto i:s_)
                    ans.pb(i);
                for(auto i:f_)
                    ans.pb(i);
            }
        }
    }
    return ans;
}
// int main()
// {
//     int n;
//     cin>>n;
//    auto tp= construct_permutation(n);
//    for(auto k:tp)
//    {
//     cout<<k<<' ';
//    }
//    cout<<endl;
// }

Compilation message (stderr)

perm.cpp: In function 'std::vector<int> construct_permutation(long long int)':
perm.cpp:85:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   85 |                 for(int i=0;i<f_.size();i++)
      |                             ~^~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 87.000000003 / 90