Submission #839746

#	Time	Username	Problem	Language	Result	Execution time	Memory
839746		model_code	Longest Trip (IOI23_longesttrip)	C++17	85 / 100	19 ms	400 KiB

longesttrip

// partially_correct/sol_na_D1_stable.cpp

#include "longesttrip.h"
#include <deque>
#include <functional>
#include <algorithm>
#include <iostream>

std::vector<int> longest_trip(int N, int D)
{
    srand(time(0));
    std::vector<int> ids(N);
    for (int i = 0; i < N; i++)
        ids[i] = i;
    random_shuffle(ids.begin(), ids.end());

    std::deque<int> A = {ids[0]}, B;
    for (int j = 1; j < N; ++j)
    {
        int i = ids[j];
        if (A.size() < B.size())
            A.swap(B);
        if (are_connected({A.back()}, {i}))
        {
            A.push_back(i);
        }
        else if (B.empty() || are_connected({B.back()}, {i}))
        {
            B.push_back(i);
        }
        else
        {
            while (!B.empty())
            {
                A.push_back(B.back());
                B.pop_back();
            }
            B = {i};
        }
    }
    if (A.size() > B.size())
        A.swap(B);

    std::function<std::vector<int>(std::deque<int>, std::deque<int>)> solve;
    solve = [&](std::deque<int> A, std::deque<int> B) -> std::vector<int>
    {
        if (A.size() > B.size())
            A.swap(B);
        if (B.size() == N)
            return std::vector<int>(B.begin(), B.end());

        bool x = are_connected({A.back()}, {B.front()});
        bool y = are_connected({A.back()}, {B.back()});
        if (x)
        {
            while (!A.empty())
            {
                B.push_front(A.back());
                A.pop_back();
            }
            return std::vector<int>(B.begin(), B.end());
        }
        else if (y)
        {
            while (!A.empty())
            {
                B.push_back(A.back());
                A.pop_back();
            }
            return std::vector<int>(B.begin(), B.end());
        }
        else
        {
            if (are_connected(std::vector<int>(A.begin(), A.end()), std::vector<int>(B.begin(), B.end())))
            {
                int L = 0, R = A.size() - 1;
                auto BB = std::vector<int>(B.begin(), B.end());
                while (L < R)
                {
                    int mid = (L + R) / 2;
                    if (are_connected(std::vector<int>(A.begin(), A.begin() + mid + 1), BB))
                    {
                        R = mid;
                    }
                    else
                    {
                        L = mid + 1;
                    }
                }
                int firstA = L;
                L = 0;
                R = B.size() - 1;
                auto AA = std::vector<int>(A.begin(), A.begin() + firstA + 1);
                while (L < R)
                {
                    int mid = (L + R) / 2;
                    if (are_connected(AA, std::vector<int>(B.begin(), B.begin() + mid + 1)))
                    {
                        R = mid;
                    }
                    else
                    {
                        L = mid + 1;
                    }
                }
                int firstB = L;

                while (firstB > 0)
                {
                    B.push_back(B.front());
                    B.pop_front();
                    firstB--;
                }

                std::deque<int> lst;
                if (firstA >= (int)A.size() / 2)
                {
                    while (firstA >= 0)
                    {
                        lst.push_back(A.front());
                        A.pop_front();
                        firstA--;
                    }
                }
                else
                {
                    while (firstA < (int)A.size())
                    {
                        lst.push_front(A.back());
                        A.pop_back();
                    }
                    reverse(lst.begin(), lst.end());
                }
                while (!lst.empty())
                {
                    B.push_front(lst.back());
                    lst.pop_back();
                }
                return solve(A, B);
            }
            else
            {
                return std::vector<int>(B.begin(), B.end());
            }
        }
    };

    return solve(A, B);
}

Compilation message (stderr)

longesttrip.cpp: In lambda function:
longesttrip.cpp:49:22: warning: comparison of integer expressions of different signedness: 'std::deque<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   49 |         if (B.size() == N)
      |             ~~~~~~~~~^~~~

• Subtask 0: 0 / 0
• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 25 / 25
• Subtask 4: 45 / 60