Understanding Stacks and Queues

Stack (Last In, First Out)

A stack is like a stack of plates. You place plates on top, and when you need one, you take the one from the top.

• Start: []
• Push 3, 7, 5: [3, 7, 5]
• Pop: [3, 7]
• Push 9: [3, 7, 9]
• Pop: [3, 7]

Queue (First In, First Out)

A queue is like a line at a bank. The first person in line is the first person served, and new people join the line at the end.

• Start: []
• Enqueue 3, 7, 5: [3, 7, 5]
• Dequeue: [7, 5]
• Enqueue 9: [7, 5, 9]
• Dequeue: [5, 9]