Submission #757797

#	Time	Username	Problem	Language	Result	Execution time	Memory
757797		borisAngelov	The Big Prize (IOI17_prize)	C++17	97.75 / 100	59 ms	5208 KiB

prize

#include "prize.h"

#include <iostream>
#include <vector>
#include <random>
#include <ctime>

using namespace std;

const int maxn = 200005;

int N;

int max_result = 0;

vector<int> results[maxn];

int divide(int l, int r, int removed_from_left, int removed_from_right)
{
    if (l > r)
    {
        return 0;
    }

    int mid = (l + r) / 2;
    vector<int> curr;

    while (mid <= r)
    {
        //curr = ask(mid);

        if (!results[mid].empty())
        {
            curr = results[mid];
        }
        else
        {
            curr = ask(mid);
            results[mid].push_back(curr[0]);
            results[mid].push_back(curr[1]);
        }

        if (curr[0] + curr[1] == 0)
        {
            return mid;
        }

        if (curr[0] + curr[1] == max_result)
        {
            break;
        }

        ++mid;
    }

    if (mid <= r)
    {
        curr[0] -= (removed_from_left - (mid - (l + r) / 2));
        curr[1] -= removed_from_right;

        if (curr[0] > 0)
        {
            int idx = divide(l, (l + r) / 2 - 1, removed_from_left, removed_from_right + curr[1] + (mid - (l + r) / 2));

            if (idx != 0)
            {
                return idx;
            }
        }

        if (curr[1] > 0)
        {
            int idx = divide(mid + 1, r, removed_from_left + curr[0] + (mid - (l + r) / 2), removed_from_right);

            if (idx != 0)
            {
                return idx;
            }
        }

        return 0;
    }
    else
    {
        mid = (l + r) / 2 - 1;

        while (mid >= l)
        {
            if (!results[mid].empty())
            {
                curr = results[mid];
            }
            else
            {
                curr = ask(mid);
                results[mid].push_back(curr[0]);
                results[mid].push_back(curr[1]);
            }

            if (curr[0] + curr[1] == 0)
            {
                return mid;
            }

            if (curr[0] + curr[1] == max_result)
            {
                return mid;
            }

            --mid;
        }

        if (mid == l - 1)
        {
            return 0;
        }

        curr[0] -= removed_from_left;

        if (curr[0] > 0)
        {
            return divide(l, mid - 1, removed_from_left, removed_from_right + (r - mid));
        }

        return 0;
    }

    return 0;
}

int find_best(int n)
{
    N = n;

    for (int i = 0; i < 470; ++i)
    {
        int idx = rand() % n;

        while (!results[idx].empty())
        {
            idx = rand() % n;
        }

        vector<int> curr_result = ask(idx);

        results[idx].push_back(curr_result[0]);
        results[idx].push_back(curr_result[1]);

        if (curr_result[0] + curr_result[1] == 0)
        {
            return idx;
        }

        max_result = max(max_result, curr_result[0] + curr_result[1]);
    }

    return divide(0, N - 1, 0, 0);
}

• Subtask 1: 20 / 20
• Subtask 2: 77.75 / 80