Stack & Queue — Python Technical Interview Questions & Answers

Stack & Queue

Stack & Queue

  • Stack = LIFO. Use a list: append + pop(). Queue = FIFO. Use collections.deque: append + popleft() (list pop(0) is slow).
  • Board: stack [1,2,3] pop → 3. Queue Asha,Ravi popleft → Asha first.
  • Stack & Queue — output: stack pop B (LIFO) then queue Asha (FIFO).

Technical Interview Tip: LIFO vs FIFO + which Python type.

Code Examples for Stack & Queue

Example

# Stack & Queue
from collections import deque
stack = []
stack.append("A")
stack.append("B")
print("stack pop", stack.pop())
q = deque(["Asha", "Ravi"])
print("queue", q.popleft())

Stack & Queue — output: stack pop B (LIFO) then queue Asha (FIFO).

How to Explain Stack & Queue to an Interviewer

Explain Stack & Queue as if you are teaching a junior — definition, then one tiny script.

Stack LIFO : append/pop Queue FIFO : deque popleft

What does the example print, and why?

Stack & Queue — output: stack pop B (LIFO) then queue Asha (FIFO)

What mistake do freshers make with Stack & Queue?

list.pop(0) is O(n)