2. Explain how to Tmplement a [queue [ stack] with a [singly / doubly ] linked list with the optimal Big-O? Which end(s) should you insert/remove from for the optimal Big-O? 3. Explain how to store a stack in an array with the optimal big-O. 4. Explain how a circular queue works for storing a queue in an array. 5. Write the code to perform peek() for a queue stored as an array. 6. Write the code to perform push 0 for a stack stored as a singly linked list