Submission #956441

#	Time	Username	Problem	Language	Result	Execution time	Memory
956441		Mher777	Sequence (APIO23_sequence)	C++17	0 / 100	514 ms	17892 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], p[N], pref[N], t[N * 4];
vi g[5];
int n, m, ans = 1;

void bld(int l = 1, int r = m, int pos = 1) {
    if (l == r) {
        p[l] = pos;
        return;
    }
    int mid = (l + r) / 2;
    bld(l, mid, 2 * pos);
    bld(mid + 1, r, 2 * pos + 1);
}

int qry(int l, int r, int tl = 1, int tr = m, int pos = 1) {
    if (l > r) return MAX;
    if (l == tl && r == tr) return t[pos];
    int mid = (tl + tr) / 2;
    if (mid >= r) {
        return qry(l, r, tl, mid, 2 * pos);
    }
    if (mid < l) {
        return qry(l, r, mid + 1, tr, 2 * pos + 1);
    }
    return min(qry(l, mid, tl, mid, 2 * pos), qry(mid + 1, r, mid + 1, tr, 2 * pos + 1));
}

void upd(int pos, int val) {
    pos = p[pos];
    t[pos] = val;
    pos /= 2;
    while (pos) {
        t[pos] = min(t[2 * pos], t[2 * pos + 1]);
        pos /= 2;
    }
}

void solve_1(int type) {
    for (int i = 1; i <= m; ++i) {
        int val = pref[i], mx = val + 1;
        if (type == 1 && i % 2) ++mx;
        else if (type == 2 && !(i % 2)) ++mx;
        if (qry(i + 1, m) > mx) continue;
        int l = i + 1, r = m, mid, ind = i;
        while (l < r) {
            mid = (l + r) / 2;
            if (qry(mid + 1, r) <= mx) {
                l = ind = mid + 1;
            }
            else if (qry(l, mid) <= mx) {
                r = ind = mid;
            }
            else {
                break;
            }
        }
        ans = max(ans, ind - i + 1);
    }
}

int sequence(int N, std::vector<int> A) {
    n = N;
    g[1] = { 0 };
    g[2] = { 0 };
    g[3] = { 0 };
    for (int i = 1; i <= n; ++i) {
        a[i] = A[i - 1];
        g[a[i]].pub(i);
        pref[i] = pref[i - 1];
        if (a[i] > 1) ++pref[i];
        else --pref[i];
    }
    m = (int)g[1].size() - 1;
    bld();
    for (int i = 1; i <= m; ++i) {
        if (i % 2) upd(i, MAX);
        else upd(i, pref[g[1][i]]);
    }
    solve_1(1);
    for (int i = 1; i <= m; ++i) {
        if (i % 2) upd(i, pref[g[1][i]]);
        else upd(i, MAX);
    }
    solve_1(2);
    swap(g[1], g[3]);
    for (int i = 1; i <= n; ++i) {
        pref[i] = pref[i - 1];
        if (a[i] < 3) ++pref[i];
        else --pref[i];
    }
    m = (int)g[1].size() - 1;
    bld();
    for (int i = 1; i <= m; ++i) {
        if (i % 2) upd(i, MAX);
        else upd(i, pref[g[1][i]]);
    }
    solve_1(1);
    for (int i = 1; i <= m; ++i) {
        if (i % 2) upd(i, pref[g[1][i]]);
        else upd(i, MAX);
    }
    solve_1(2);
    return ans;
}

/*
7
3 2 1 3 2 3 1
*/

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