#pragma GCC optimize("O3") #include using namespace std; #define int long long #define fastio ios_base::sync_with_stdio(0); cin.tie(0) const int N = 1e6 + 5; signed main() { fastio; /* deque q; q.size(); q.empty(); q.back(); q.push_back(); q.pop_back(); q.front(); q.push_front(); q.pop_front(); */ deque q; q.push_front(5); q.push_back(2); q.push_front(7); for(int i = 0; i < q.size(); i++){ cout << q[i] << " "; } cout << '\n'; // 7 5 2 }