STL deque写法
#include<bits/stdc++.h>
using namespace std;
const int N = 1e6 + 10;
deque<int>q;
int a[N];
int n, m;
int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    cin >> n >> m;
    for(int i = 1;i <= n;i++)cin >> a[i];

    for(int i = 1;i <= n;i++)
    {
        while(q.size() && a[i] < a[q.back()])q.pop_back();
        q.push_back(i);
        if(i >= m)
        {
            while(q.size() && i - q.front() >= m)q.pop_front();
            cout << a[q.front()] << " ";
        }
    }
    cout << endl;

    deque<int>q;
    for(int i = 1;i <= n;i++)
    {
        while(q.size() && a[i] > a[q.back()])q.pop_back();
        q.push_back(i);
        if(i >= m)
        {
            while(q.size() && i - q.front() >= m)q.pop_front();
            cout << a[q.front()] << " ";
        }
    }
}