Data Structure: How to Implement the stack using two queues?

Pop Efficient:

  1. Push(x):
    1. Enqueue x on q2
    2. Enqueue each elements on q1 on to q2
    3. Switch names between q1 and q2
  2. Pop():
    1. Dequeue from q1.


Push Efficient:

  • Push(x):
    1. Enqueue x on q2
  • Pop():
    1. Dequeue each element except the last element from q2 to q1.
    2. Dequeue the last element on q2.
    3. Switch names between q1 and q2.

 

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