Submission #760270

#	Time	Username	Problem	Language	Result	Execution time	Memory
760270		danikoynov	Sequence (APIO23_sequence)	C++17	100 / 100	1144 ms	55512 KiB

sequence

#include "sequence.h"

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

const int maxn = 5e5 + 10;

struct node
{
    int lb, rb;

    node(int _lb = 1e9, int _rb = -1e9)
    {
        lb = _lb;
        rb = _rb;
    }
};

node merge_node(node lf, node rf)
{
    node nd;
    nd.lb = min(lf.lb, rf.lb);
    nd.rb = max(lf.rb, rf.rb);
    return nd;
}

node tree[4 * maxn];
int lazy_exp[4 * maxn], lazy_shift[4 * maxn];
void build_tree(int root, int left, int right)
{
    if (left == right)
    {
        tree[root] = node(left, left);
        return;
    }

    int mid = (left + right) / 2;
    build_tree(root * 2, left, mid);
    build_tree(root * 2 + 1, mid + 1, right);
    tree[root] = merge_node(tree[root * 2], tree[root * 2 + 1]);
}

void push_lazy(int root, int left, int right)
{
    tree[root].lb -= lazy_exp[root];
    tree[root].rb += lazy_exp[root];
    tree[root].lb += lazy_shift[root];
    tree[root].rb += lazy_shift[root];
    if (left != right)
    {
        lazy_exp[2 * root] += lazy_exp[root];
        lazy_exp[2 * root + 1] += lazy_exp[root];
        lazy_shift[2 * root] += lazy_shift[root];
        lazy_shift[2 * root + 1] += lazy_shift[root];
    }

    lazy_exp[root] = lazy_shift[root] = 0;
}

void update_exp(int root, int left, int right, int qleft, int qright, int val)
{
    push_lazy(root, left, right);
    if (left > qright || right < qleft)
        return;

    if (left >= qleft && right <= qright)
    {
        lazy_exp[root] += val;
        push_lazy(root, left, right);
        return;
    }

    int mid = (left + right) / 2;
    update_exp(root * 2, left, mid, qleft, qright, val);
    update_exp(root * 2 + 1, mid + 1, right, qleft, qright, val);

    tree[root] = merge_node(tree[root * 2], tree[root * 2 + 1]);
}

void update_shift(int root, int left, int right, int qleft, int qright, int val)
{
    push_lazy(root, left, right);
    if (left > qright || right < qleft)
        return;

    if (left >= qleft && right <= qright)
    {
        lazy_shift[root] += val;
        push_lazy(root, left, right);
        return;
    }

    int mid = (left + right) / 2;
    update_shift(root * 2, left, mid, qleft, qright, val);
    update_shift(root * 2 + 1, mid + 1, right, qleft, qright, val);

    tree[root] = merge_node(tree[root * 2], tree[root * 2 + 1]);
}

node query(int root, int left, int right, int qleft, int qright)
{
    push_lazy(root, left, right);
    if (left > qright || right < qleft)
        return node();

    if (left >= qleft && right <= qright)
        return tree[root];

    int mid = (left + right) / 2;
    return merge_node(query(root * 2, left, mid, qleft, qright),
                      query(root * 2 + 1, mid + 1, right, qleft, qright));
}

vector < int > occ[maxn];
int val[maxn], pref[maxn];


int sequence(int N, vector<int> A)
{
    A.insert(A.begin(), 0);
    for (int i = 1; i <= N; i ++)
        occ[A[i]].push_back(i);

        build_tree(1, 0, N);
    int ans = 0;
    for (int x = 1; x <= N; x ++)
    {
        for (int i : occ[x - 1])
        {
            update_shift(1, 0, N, i, N, -1);
        }

        for (int i : occ[x])
        {
            update_shift(1, 0, N, i, N, -1);
        }
        /**for (int i = 1; i <= N; i ++)
        {
            if (A[i] < x)
                val[i] = -1;
            else
            if (A[i] == x)
            val[i] = 0;
            else
                val[i] = 1;
            pref[i] = pref[i - 1] + val[i];
        }*/


    int beg = ans + 1;
        for (int i = ans + 1; i < occ[x].size(); i ++)
            update_exp(1, 0, N, occ[x][i], N, 1);
        int i = 0;
        while(i < occ[x].size())
        {
            int j = i + ans;
            if (j >= occ[x].size())
                break;

            ///cout << pref[r] << endl;
            int l = occ[x][i], r = occ[x][j];
            int min_lf = 1e9, max_lf = -1e9;
            int min_rf = 1e9, max_rf = -1e9;
            /**int d = 0;
            for (int p = l - 1; p >= 0; p --)
            {
                if (A[p] == x)
                    d ++;
                min_lf = min(min_lf, pref[p] - d);
                max_lf = max(max_lf, pref[p] + d);
            }
            d = 0;
            for (int p = r; p <= N; p ++)
            {
                if (A[p] == x && p != r)
                    d ++;
                min_rf = min(min_rf, pref[p] - d);
                max_rf = max(max_rf, pref[p] + d);
            }*/
            node lf = query(1, 0, N, 0, l - 1);
            min_lf = lf.lb;
            max_lf = lf.rb;
            node rf = query(1, 0, N, r, N);
            min_rf = rf.lb;
            max_rf = rf.rb;

            max_rf += (j - i + 1);
            min_rf -= (j - i + 1);
            /**cout << "-----------" << endl;
            cout << x << " " << i << " " << j << " " << ans << endl;
            cout << min_lf << " " << max_lf << " " << min_rf << " " << max_rf << endl;
            cout << rf.lb << " : " << rf.rb << endl;*/
            if (max(min_rf, min_lf) <= min(max_rf, max_lf))
            {
                ///cout << x << " " << i << " " << j << endl;
                ans ++;
            }
            else
            {
                update_exp(1, 0, N, 0, l, 1);
                i ++;
            }
            if (j + 1 != occ[x].size())
            update_exp(1, 0, N, occ[x][j + 1], N, -1);
        }
        for (int p = 0; p < i; p ++)
            update_exp(1, 0, N, 0, occ[x][p], -1);

    }
    return ans;
}

Compilation message (stderr)

sequence.cpp: In function 'int sequence(int, std::vector<int>)':
sequence.cpp:121:5: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
  121 |     for (int i = 1; i <= N; i ++)
      |     ^~~
sequence.cpp:124:9: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
  124 |         build_tree(1, 0, N);
      |         ^~~~~~~~~~
sequence.cpp:151:33: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  151 |         for (int i = ans + 1; i < occ[x].size(); i ++)
      |                               ~~^~~~~~~~~~~~~~~
sequence.cpp:154:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  154 |         while(i < occ[x].size())
      |               ~~^~~~~~~~~~~~~~~
sequence.cpp:157:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  157 |             if (j >= occ[x].size())
      |                 ~~^~~~~~~~~~~~~~~~
sequence.cpp:203:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  203 |             if (j + 1 != occ[x].size())
      |                 ~~~~~~^~~~~~~~~~~~~~~~
sequence.cpp:150:9: warning: unused variable 'beg' [-Wunused-variable]
  150 |     int beg = ans + 1;
      |         ^~~

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