Submission #954428

#	Time	Username	Problem	Language	Result	Execution time	Memory
954428		Mher777	Sequence (APIO23_sequence)	C++17	28 / 100	2086 ms	10104 KiB

sequence

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <iomanip>
#include <array>
#include <string>
#include <algorithm>
#include <cmath>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <bitset>
#include <list>
#include <iterator>
#include <numeric>
#include <complex>
#include <utility>
#include <random>
#include <cassert>
#include <fstream>
#include "sequence.h"
using namespace std;
mt19937 rnd(7069);
typedef int itn;
typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef float fl;
typedef long double ld;
using vi = vector<int>;
using vll = vector<ll>;
using mii = map<int, int>;
using mll = map<ll, ll>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
#define ff first
#define ss second
#define pub push_back
#define pob pop_back
#define puf push_front
#define pof pop_front
#define mpr make_pair
#define yes cout<<"Yes\n"
#define no cout<<"No\n"
#define all(x) (x).begin(), (x).end()
const int MAX = int(2e9 + 5);
const ll MAXL = ll(1e18) + 5ll;

const int N = 500005;
int a[N], f[N];
int n;

void add_fen(int ind, int val) {
    while (ind <= n) {
        f[ind] += val;
        ind += (ind & -ind);
    }
}

int sum_fen(int ind) {
    int ret = 0;
    while (ind) {
        ret += f[ind];
        ind -= (ind & -ind);
    }
    return ret;
}

int qry_fen(int l, int r) {
    return sum_fen(r) - sum_fen(l - 1);
}

int sol1() {
    int len;
    int ret = 0;
    vi cnt(n + 1);
    for (int i = 1; i <= n; ++i) {
        cnt.assign(n + 1, 0);
        for (int j = 1; j <= n; ++j) add_fen(j, -qry_fen(j, j));
        len = 0;
        for (int j = i; j <= n; ++j) {
            ++cnt[a[j]];
            add_fen(a[j], 1);
            ++len;
            int ind1, ind2;
            if (len % 2) {
                ind1 = ind2 = len / 2 + 1;
            }
            else {
                ind1 = len / 2;
                ind2 = len / 2 + 1;
            }
            int l = 1, r = n, mid;
            while (l <= r) {
                mid = (l + r) / 2;
                int index = qry_fen(1, mid);
                int cnt_x = cnt[mid];
                if (index - cnt_x >= ind1) {
                    r = mid - 1;
                }
                else if (index < ind1) {
                    l = mid + 1;
                }
                else if (cnt_x) {
                    ret = max(ret, cnt_x);
                    break;
                }
                else {
                    r = mid - 1;
                }
            }
            l = 1, r = n;
            while (l <= r) {
                mid = (l + r) / 2;
                int index = qry_fen(1, mid);
                int cnt_x = cnt[mid];
                if (index - cnt_x >= ind2) {
                    r = mid - 1;
                }
                else if (index < ind2) {
                    l = mid + 1;
                }
                else if (cnt_x) {
                    ret = max(ret, cnt_x);
                    break;
                }
                else {
                    r = mid - 1;
                }
            }
        }
    }
    return ret;
}

int sequence(int N, std::vector<int> A) {
    n = N;
    for (int i = 1; i <= n; ++i) {
        a[i] = A[i - 1];
    }
    return sol1();
}

/*
7
1 2 3 1 2 1 3
3

9
1 1 2 3 4 3 2 1 1
2

14
2 6 2 5 3 4 2 1 4 3 5 6 3 2
3
*/

• 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