Submission #946343

#	Time	Username	Problem	Language	Result	Execution time	Memory
946343		Nhoksocqt1	Sequence (APIO23_sequence)	C++17	28 / 100	2062 ms	34896 KiB

sequence

#ifndef Nhoksocqt1
    #include "sequence.h"
#endif // Nhoksocqt1
#include<bits/stdc++.h>
using namespace std;

#define inf 0x3f3f3f3f
#define sz(x) int((x).size())
#define fi first
#define se second
typedef long long ll;
typedef pair<int, int> ii;

template<class X, class Y>
	inline bool maximize(X &x, const Y &y) {return (x < y ? x = y, 1 : 0);}
template<class X, class Y>
	inline bool minimize(X &x, const Y &y) {return (x > y ? x = y, 1 : 0);}

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int Random(int l, int r) {
    return uniform_int_distribution<int>(l, r)(rng);
}

const int MAXN = 500005;

int val[MAXN], cnt[MAXN], nArr;

int sub2(void) {
    int res(1);
    for (int l = 1; l <= nArr; ++l) {
        set<int> Set;
        int pos(val[l]), cntPos(1);
        Set.insert(pos);
        ++cnt[pos];

        for (int r = l + 1; r <= nArr; ++r) {
            cntPos += (val[r] <= pos);
            if(++cnt[val[r]] == 1)
                Set.insert(val[r]);

            while(cntPos < (r - l + 1) / 2 + 1) {
                auto it = Set.lower_bound(pos); ++it;
                assert(it != Set.end());
                pos = *it;
                cntPos += cnt[pos];
            }

            while(cntPos - cnt[pos] >= (r - l + 1) / 2 + 1) {
                cntPos -= cnt[pos];
                auto it = Set.lower_bound(pos);
                assert(it != Set.begin()); --it;
                pos = *it;
            }

            //cout << l << ' ' << r << ' ' << pos << ' ' << cntPos << '\n';
            res = max(res, cnt[pos]);
            if((r - l + 1) % 2 == 0 && cntPos - cnt[pos] >= (r - l + 1) / 2) {
                auto it = Set.lower_bound(pos);
                assert(it != Set.begin()); --it;
                res = max(res, cnt[*it]);
            }
        }

        for (int r = l; r <= nArr; ++r)
            --cnt[val[r]];
    }

    return res;
}

int sequence(int _N, vector<int> _A) {
    nArr = _N;
    for (int i = 1; i <= nArr; ++i)
        val[i] = _A[i - 1];

    if(nArr <= 2000)
        return sub2();
}

#ifdef Nhoksocqt1

int main(void) {
    ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);

    #define TASK "sequence"
    if(fopen(TASK".inp", "r")) {
        freopen(TASK".inp", "r", stdin);
        freopen(TASK".out", "w", stdout);
    }

    vector<int> _A;
    int _N;
    cin >> _N;

    _A.resize(_N);
    for (int i = 0; i < _N; ++i)
        cin >> _A[i];

    int ans = sequence(_N, _A);
    cout << "ANSWER: " << ans << '\n';

    return 0;
}

#endif // Nhoksocqt1

Compilation message (stderr)

sequence.cpp: In function 'int sequence(int, std::vector<int>)':
sequence.cpp:78:1: warning: control reaches end of non-void function [-Wreturn-type]
   78 | }
      | ^

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