4 ms·

Neat, it's always best to look at the source. To be clear, a deque can be implemented on top of an array and still have constant time operations on the head.

• sicp-enjoyer 4y ago
  If it's not constant time on both ends, it's not a deque. You can already insert items at any index in an array with linear cost.
  • sgtnoodle 4y ago
    I invite you to think about the problem for a while, and try to think of a way to implement a performant deque on top of a resize-able array. I promise you it's possible.
    • eru 4y ago
      I don't think the comment you replied to disagreed with that.