Submission #1057255

#	Time	Username	Problem	Language	Result	Execution time	Memory
1057255		alexdd	Sequence (APIO23_sequence)	C++17	20 / 100	728 ms	52816 KiB

sequence

#include "sequence.h"
#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9;
pair<int,int> combine(pair<int,int> x, pair<int,int> y)
{
    return {min(x.first,y.first),max(x.second,y.second)};
}
pair<int,int> aint[1100000][2];
int lazy[1100000];
void build(int nod, int st, int dr)
{
    if(st==dr)
    {
        if(st%2==0)
        {
            aint[nod][0]={0,0};
            aint[nod][1]={INF,-INF};
        }
        else
        {
            aint[nod][1]={0,0};
            aint[nod][0]={INF,-INF};
        }
        return;
    }
}
void propagate(int nod)
{
    if(!lazy[nod])
        return;
    lazy[nod*2]+=lazy[nod];
    lazy[nod*2+1]+=lazy[nod];
    aint[nod*2][0].first+=lazy[nod];
    aint[nod*2][0].second+=lazy[nod];
    aint[nod*2+1][0].first+=lazy[nod];
    aint[nod*2+1][0].second+=lazy[nod];
    aint[nod*2][1].first+=lazy[nod];
    aint[nod*2][1].second+=lazy[nod];
    aint[nod*2+1][1].first+=lazy[nod];
    aint[nod*2+1][1].second+=lazy[nod];
    lazy[nod]=0;
}
void upd(int nod, int st, int dr, int le, int ri, int newv)
{
    if(le>ri)
        return;
    if(le==st && dr==ri)
    {
        lazy[nod]+=newv;
        aint[nod][0].first+=newv;
        aint[nod][0].second+=newv;
        aint[nod][1].first+=newv;
        aint[nod][1].second+=newv;
        return;
    }
    propagate(nod);
    int mij=(st+dr)/2;
    upd(nod*2,st,mij,le,min(mij,ri),newv);
    upd(nod*2+1,mij+1,dr,max(mij+1,le),ri,newv);
    aint[nod][0] = combine(aint[nod*2][0], aint[nod*2+1][0]);
    aint[nod][1] = combine(aint[nod*2][1], aint[nod*2+1][1]);
}
pair<int,int> qry(int nod, int st, int dr, int le, int ri, int c)
{
    if(le>ri)
        return {INF,-INF};
    if(le==st && dr==ri)
        return aint[nod][c];
    propagate(nod);
    int mij=(st+dr)/2;
    return combine(qry(nod*2,st,mij,le,min(mij,ri),c),
                   qry(nod*2+1,mij+1,dr,max(mij+1,le),ri,c));
}
bool verif(int le, int ri, int cnt0, int N)
{
    pair<int,int> x[2] = {qry(1,0,N,0,le-1,0), qry(1,0,N,0,le-1,1)};
    pair<int,int> y[2] = {qry(1,0,N,ri,N,0), qry(1,0,N,ri,N,1)};

    for(int p=0;p<2;p++)
    {
        for(int q=0;q<2;q++)
        {
            pair<int,int> a = x[p], b = y[q];
            if(a.first > b.first)
                swap(a,b);
            if(p==q)
            {
                if(a.second + cnt0 - 1 >= b.first)
                    return 1;
            }
            else
            {
                if(a.second + cnt0 >= b.first)
                    return 1;
            }
        }
    }
    return 0;
}
vector<int> pozs[500005];
int sequence(int N, std::vector<int> A)
{
    build(1,0,N);
    for(int i=1;i<=N;i++)
    {
        upd(1,0,N,i,N,+1);
        pozs[A[i-1]].push_back(i);
    }
    int mxm=1;
    for(int val=1;val<=N;val++)
    {
        for(auto x:pozs[val])
            upd(1,0,N,x,N,-1);

        int st=0;
        for(int i=0;i<pozs[val].size();i++)
        {
            while(!verif(pozs[val][st],pozs[val][i],i-st+1,N))
                st++;
            mxm = max(mxm, i-st+1);
        }

        for(auto x:pozs[val])
            upd(1,0,N,x,N,-1);
    }
    return mxm;
}

Compilation message (stderr)

sequence.cpp: In function 'int sequence(int, std::vector<int>)':
sequence.cpp:117:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  117 |         for(int i=0;i<pozs[val].size();i++)
      |                     ~^~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 11
• Subtask 2: 0 / 17
• Subtask 3: 7 / 7
• Subtask 4: 0 / 12
• Subtask 5: 13 / 13
• Subtask 6: 0 / 22
• Subtask 7: 0 / 18