Submission #760191

#	Time	Username	Problem	Language	Result	Execution time	Memory
760191		danikoynov	Sequence (APIO23_sequence)	C++17	35 / 100	304 ms	31532 KiB

sequence

#include "sequence.h"

#include <bits/stdc++.h>
using namespace std;

const int maxn = 5e5 + 10;
int occ[maxn];
vector < pair < int, int > > ranges[maxn];
int sequence(int N, vector<int> A)
{
    if (N > 2e3)
    {
        int len = 1;
        for (int i = 1; i < N; i ++)
        {
            if (A[i] == A[i - 1])
                len ++;
            else
            {
                ranges[A[i - 1]].push_back({i - len, i - 1});
                len = 1;
            }
        }
        ranges[A[N - 1]].push_back({N - len, N - 1});

        int ans = 1;
        for (int i = 1; i <= N; i ++)
        {
            for (pair < int, int > cur : ranges[i])
                ans = max(ans, cur.second - cur.first + 1);

            if (ranges[i].size() == 2)
            {
                pair < int, int > lf, rf;
                lf = ranges[i][0];
                rf = ranges[i][1];
                int big = rf.first - lf.second - 1;
                int small = lf.first + N - rf.second - 1;
                int mid = (lf.second - lf.first + 1 + rf.second - rf.first + 1);
                if (big > small + mid)
                    continue;
                    ///cout << i << " : " << small << " : " << big << " : " << mid << endl;
                    //cout << lf.first << " " << rf.second << endl;
                ans = max(ans, mid);
            }
        }
        return ans;
    }
    else
    {
    multiset < int > lf, rf;
    int ans = 1;
    for (int i = 0; i < N; i ++)
    {
        for (int j = 0; j <= N; j ++)
            occ[j] = 0;

        lf.clear();
        rf.clear();

        lf.insert(A[i]);
        occ[A[i]] ++;
        for (int j = i + 1; j < N; j ++)
        {
            occ[A[j]] ++;
            if (A[j] > *lf.rbegin())
                rf.insert(A[j]);
            else
                lf.insert(A[j]);

            while(lf.size() > rf.size() + 1)
            {
                int x = *lf.rbegin();
                lf.erase(lf.find(x));
                rf.insert(x);
            }
            while(rf.size() > lf.size())
            {
                int x = *rf.begin();
                rf.erase(rf.find(x));
                lf.insert(x);
            }

            if ((j - i + 1) % 2 == 0)
            {
                ans = max(ans, occ[*lf.rbegin()]);
                ans = max(ans, occ[*rf.begin()]);
            }
            else
            {
                ans = max(ans, occ[*lf.rbegin()]);
            }
        }
    }
    return ans;
    }
}

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