Stacks (last-in, first-out) in Intro to Computing - Draw & Build Visually

Draw This - beginner

Draw a diagram showing a stack with the following sequence of operations: 1. Push 10 2. Push 20 3. Push 30 4. Pop (remove top element) 5. Push 40 Show the stack after each operation and label the top of the stack clearly.

10 minutes

Hint 1

Hint 2

Hint 3

Hint 4

Grading Criteria

Stack drawn as vertical column

Top of stack clearly labeled after each operation

Push operations add new element on top

Pop operation removes the top element

Stack state correctly shown after each step

All five operations represented in order

Solution

Initial stack (empty):
+-----+
|     | <- top (empty)
+-----+

After Push 10:
+-----+
|  10 | <- top
+-----+

After Push 20:
+-----+
|  20 | <- top
+-----+
|  10 |
+-----+

After Push 30:
+-----+
|  30 | <- top
+-----+
|  20 |
+-----+
|  10 |
+-----+

After Pop (remove 30):
+-----+
|  20 | <- top
+-----+
|  10 |
+-----+

After Push 40:
+-----+
|  40 | <- top
+-----+
|  20 |
+-----+
|  10 |
+-----+

This diagram shows the stack after each operation:

1. Initial stack: The stack is empty.
2. Push 10: 10 is added to the top.
3. Push 20: 20 is added on top of 10.
4. Push 30: 30 is added on top of 20.
5. Pop: The top element 30 is removed, so 20 becomes the top.
6. Push 40: 40 is added on top of 20.

The top of the stack is always the last item added that has not been removed, demonstrating the last-in, first-out (LIFO) principle.

Variations - 2 Challenges

[beginner] Draw a diagram showing a stack with these operations: 1. Push 5 2. Push 15 3. Pop 4. Pop 5. Push 25 Show the stack after each operation and label the top.

[intermediate] Draw a flowchart that shows how to perform push and pop operations on a stack. Include decision points for checking if the stack is full before push and empty before pop.