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

class GlideWindow
{
public:
    int L, R, len;
    deque<int> q;
    vector<int> arr;
    void setUp(vector<int> a)
    {
        L = R = -1;
        len = a.size();
        arr = a;
    }
    int inquire()
    {
        if (q.empty())
            return NULL;
        return arr[q.front()];
    }
    void moveL()
    {
        if (L == R)
        {
            cout << "L and R is overlaped, can't move L." << endl;
            return;
        }
        if (q.front() == ++L)
            q.pop_front();
    }
    void moveR()
    {
        if (++R == len)
        {
            cout << "R is on the right boarder of the array, can't move." << endl;
            return;
        }
        while (!q.empty() && arr[q.back()] <= arr[R])
        {
            q.pop_back();
        }
        q.push_back(R);
    }
};

int main()
{
    vector<int> arr = {1, 4, 2, 8, 5, 7};
    GlideWindow gw;
    gw.setUp(arr);
    int LorR = 0;
    while (true)
    {
        cout << "Move L or R? [1 / 2, 0 to exit]: ";
        cin >> LorR;
        if (!LorR)
            break;
        if (LorR == 1)
            gw.moveL();
        else
            gw.moveR();
        cout << "arr: ";
        for (auto i : arr)
            cout << " " << i;
        cout << endl;
        cout << "     ";
        for (int i = 0; i < arr.size(); i++)
        {
            cout << ((gw.L == i - 1) ? "L" : " ");
            cout << ((gw.R == i - 1) ? "R" : " ");
        }
        cout << endl;
        cout << "Max of the window: " << gw.inquire() << endl;
        for (int i = 0; i < 20; i++)
        {
            cout << "- ";
        }
    }
}