双端队列

#include<bits/stdc++.h>
using namespace std;
const int M = 1e6 + 10 , inf = 0x3f3f3f3f ;
int s ;
int n , k ;
int a[M] ;
int b[M] , tot ;
void solve () {
    deque<int> q ;
    deque<int>::iterator it ;
    for (int i = 0 ; i < k ; i ++) {
        if (q.empty ()) q.push_back (i);
        else {
            it = q.end () - 1 ;
            while (*it >= a[i] && !q.empty ()) {
                q.pop_back () ;
                it -- ;
            }
            q.push_back (i) ;
        }
    }
    b[tot++] = q.front () ;
    if (q.front () == 0) q.pop_front () ;
    for (int i = k ; i < n ; i ++) {
        if (q.empty ()) q.push_back (i) ;
        else {
            it = q.end () - 1 ;
            while (*it >= a[i] && !q.empty ()) {
                q.pop_back () ;
                it -- ;
            }
            q.push_back (i) ;
        }
        b[tot++] = q.front () ;
        if (q.front () == i-k+1) q.pop_front () ;
    }
    for (int i = 0 ; i < tot ; i ++) {
        printf ("%d " , a[b[i]]) ;
    } puts ("") ;
}

int main () {
    cin >> n >> k ;
    for (int i = 0 ; i < n ; i ++) cin >> a[i] ;
    solve () ;
    return 0 ;
}