Design a stack that supports getMin() in O(1) time and O(1) extra space

Design a stack that supports getMin() in O(1) time and O(1) extra space is a DSA topic. In plain words you use it for undo typing in a tiny editor. Don’t start with a slogan — start with that picture.

Smallest example: push / pop LIFO. Type it, run it, and say what you see. If you can do that from memory, you know Design a stack that supports getMin() in O(1) time and O(1) extra space.

From the example next to this theory: Design a stack that supports getMin() in O(1) time and O(1) extra space — stack is LIFO: push/pop from the same end.

Trap — pop on empty. Fix that before you talk about advanced DSA.

Viva: what is Design a stack that supports getMin() in O(1) time and O(1) extra space? Then show push / pop LIFO. Then name the trap.

Diagram

    | 3 |  ← top (pop)
    | 2 |
    | 1 |
    LIFO

Exam tip

What is Design a stack that supports getMin() in O(1) time and O(1) extra space? Show this: push / pop LIFO. Trap: pop on empty.

Example

stack = []
stack.append(10)   # push
stack.append(20)
print(stack.pop()) # 20
print(stack[-1])   # peek → 10

Design a stack that supports getMin() in O(1) time and O(1) extra space — stack is LIFO: push/pop from the same end.

Short notes

DefDesign a stack that supports getMin() in O(1) time and O(1) extra space — undo typing in a tiny editor.
Rulepush / pop LIFO
Trappop on empty
Usea tiny editor

Design a stack that supports getMin() in O(1) time and O(1) extra space

Smallest example: push / pop LIFO. Type it, run it, and say what you see. If you can do that from memory, you know Design a stack that supports getMin() in O(1) time and O(1) extra space.

From the example next to this theory: Design a stack that supports getMin() in O(1) time and O(1) extra space — stack is LIFO: push/pop from the same end.

Trap — pop on empty. Fix that before you talk about advanced DSA.

Viva: what is Design a stack that supports getMin() in O(1) time and O(1) extra space? Then show push / pop LIFO. Then name the trap.

Diagram

    | 3 |  ← top (pop)
    | 2 |
    | 1 |
    LIFO

Exam tip

What is Design a stack that supports getMin() in O(1) time and O(1) extra space? Show this: push / pop LIFO. Trap: pop on empty.

Example

stack = []
stack.append(10)   # push
stack.append(20)
print(stack.pop()) # 20
print(stack[-1])   # peek → 10

Design a stack that supports getMin() in O(1) time and O(1) extra space — stack is LIFO: push/pop from the same end.

Short notes

DefDesign a stack that supports getMin() in O(1) time and O(1) extra space — undo typing in a tiny editor.
Rulepush / pop LIFO
Trappop on empty
Usea tiny editor

Design a stack that supports getMin() in O(1) time and O(1) extra space

Example

Short notes

Questions

Design a stack that supports getMin() in O(1) time and O(1) extra space

Example

Short notes

Questions