``` #include <bits/stdc++.h> #define endl '\n' using namespace std; typedef pair<int,int> aII; using ll = long long; using ULL = unsigned long long; const int N = 1e6+5; int n, a[N], q[N]; int hh = 0, tt = -1; inline void solve() { cin >> n; for (int i = 1; i <= n; i++) cin >> a[i]; for(int i = 1;i <= n;i++) { while (hh <= tt && a[q[tt]] <= a[i]) --tt; q[++tt] = i; } for (int i = hh; i <= tt; i++) cout << a[q[i]] << ' '; } int main() { ios::sync_with_stdio(0), cin.tie(0), cout.tie(0); int _ = 1; //int _; cin >> _; while (_--) solve(); return 0; } ```

``` #include <iostream> #include <deque> using namespace std; const int N = 1000010; int a[N]; int main() { int n; cin >> n; for (int i = 1; i <= n; i++) { cin >> a[i]; } deque<int> q; for (int i = 1; i <= n; i++) { while (!q.empty() && a[q.back()] <= a[i]) q.pop_back(); q.push_back(i); } while (!q.empty()) { cout << a[q.front()] << " "; q.pop_front(); } return 0; } ```

单调队列板子 ``` #include <bits/stdc++.h> using namespace std; const int N = 1000010; int a[N]; int n; deque<int> q; int main(){ scanf("%d",&n); for (int i = 1; i <= n; ++i) { scanf("%d",&a[i]); } for (int i = 1; i <= n; ++i) { while(!q.empty() && a[q.back()] <= a[i]) q.pop_back(); q.push_back(i); } for (int i = 0; i <= q.size() - 1; ++i) { printf("%d ",a[q[i]]); } return 0; } ```