Submission #464334

#	Time	Username	Problem	Language	Result	Execution time	Memory
464334		blue	Holiday (IOI14_holiday)	C++17	24 / 100	5044 ms	6980 KiB

holiday

#include "holiday.h"
#include <vector>
#include <iostream>
#include <set>
#include <algorithm>
using namespace std;

const int maxN = 100'000;

int N;
int S;
int D;
vector<long long> A;

long long res = 0;

long long high_sum = 0;
multiset<long long> high_values;
multiset<long long> low_values;
int L;
int R;
int can_visit;

void insert_value(long long V)
{
    high_values.insert(V);
    high_sum += V;

    while(high_values.size() > max(can_visit, 0))
    {
        low_values.insert(*high_values.begin());
        high_sum -= *high_values.begin();
        high_values.erase(high_values.begin());
    }
}

void erase_value(long long V)
{
    if(low_values.find(V) != low_values.end())
    {
        low_values.erase(low_values.find(V));
    }
    else
    {
        high_values.erase(high_values.find(V));
        high_sum -= V;
    }

    while(high_values.size() + 1 <= can_visit && low_values.size() >= 1)
    {
        high_values.insert(*low_values.rbegin());
        high_sum += *low_values.rbegin();
        low_values.erase(low_values.find(*low_values.rbegin()));
    }
}

void expand_right()
{
    can_visit--;

    R++;
    insert_value(A[R]);
}

void contract_right()
{
    can_visit++;

    erase_value(A[R]);
    R--;
}

void expand_left()
{
    can_visit -= 2;

    L--;
    insert_value(A[L]);
}

void contract_left()
{
    can_visit += 2;

    erase_value(A[L]);
    L++;
}

void solve(int l1, int l2, int r1, int r2)
{
    int l = (l1+l2)/2;

    for(int l = l1; l <= l2; l++)
    {
        while(L-1 >= l)
            expand_left();

        while(R+1 <= max(r1, l))
            expand_right();

        while(L+1 <= l)
            contract_left();

        while(R-1 >= max(r1, l))
            contract_right();

        long long score = high_sum;
        int best_r = R;

        while(R+1 <= r2)
        {
            expand_right();

            if(high_sum > score)
            {
                score = high_sum;
                best_r = R;
            }

            // cerr << L << ' ' << R << ' ' << score << '\n';
            // cerr << can_visit << '\n';
            // for(int a: high_values) cerr << a << ' ';
            // cerr << '\n';
            // cerr << high_sum << '\n';
            // cerr << "\n\n";
        }

        res = max(res, score);
    }
}


long long int findMaxAttraction(int n, int start, int d, int attraction[])
{
    N = n;
    S = start;
    D = d;
    A = vector<long long>(N);
    for(int i = 0; i < N; i++) A[i] = attraction[i];

    if(D == 0) return 0;

    //part 1: first left, then right

    high_values.insert(A[S]);
    high_sum = A[S];
    L = R = S;
    can_visit = d;

    // cerr << "left, then right\n";

    solve(0, S, 0, N-1);


    reverse(A.begin(), A.end());

    S = N-1 - S;
    high_values.clear();
    low_values.clear();

    // cerr << "new S = " << S << '\n';
    high_values.insert(A[S]);
    high_sum = A[S];
    L = R = S;
    can_visit = d;
    // cerr << "right, then left\n";
    solve(0, S, 0, N-1);

    return res;
}

Compilation message (stderr)

holiday.cpp: In function 'void insert_value(long long int)':
holiday.cpp:29:30: warning: comparison of integer expressions of different signedness: 'std::multiset<long long int>::size_type' {aka 'long unsigned int'} and 'const int' [-Wsign-compare]
   29 |     while(high_values.size() > max(can_visit, 0))
      |           ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~
holiday.cpp: In function 'void erase_value(long long int)':
holiday.cpp:49:34: warning: comparison of integer expressions of different signedness: 'std::multiset<long long int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   49 |     while(high_values.size() + 1 <= can_visit && low_values.size() >= 1)
      |           ~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~
holiday.cpp: In function 'void solve(int, int, int, int)':
holiday.cpp:108:13: warning: variable 'best_r' set but not used [-Wunused-but-set-variable]
  108 |         int best_r = R;
      |             ^~~~~~
holiday.cpp:91:9: warning: unused variable 'l' [-Wunused-variable]
   91 |     int l = (l1+l2)/2;
      |         ^

• Subtask 1: 7 / 7
• Subtask 2: 0 / 23
• Subtask 3: 17 / 17
• Subtask 4: 0 / 53