单调队列挺有意思

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#include <bits/stdc++.h>
using namespace std;
const int N = 1e6 + 10;

int n, m;
int a[N];
int q[N];
int mx[N], mn[N];

int main() {
    cin >> n >> m;
    int top, tail;
    for (int i = 1; i <= n; i++)
        cin >> a[i];
    top = tail = 0;
    for (int i = 1; i <= n; i++) {
        while (top < tail && a[q[tail - 1]] <= a[i])
            tail--;
        q[tail++] = i;
        while (i > m && q[top] <= i - m)
            top++;
        mx[i] = a[q[top]];
    }

    top = tail = 0;
    for (int i = 1; i <= n; i++) {
        while (top < tail && a[q[tail - 1]] >= a[i])
            tail--;
        q[tail++] = i;
        while (i > m && q[top] <= i - m)
            top++;
        mn[i] = a[q[top]];
    }
    for (int i = m; i <= n; ++i) cout << mn[i] << ' '; cout << endl;
    for (int i = m; i <= n; ++i) cout << mx[i] << ' '; cout << endl;
    return 0;
}