Largest Rectangle in Histogram Using Stack in DSA Python - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the stack as an empty list.

DSA Python

stack = [1]

Drag options to blanks, or click blank then click option'

A[]

B{}

CNone

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using curly braces {} which creates a set or dictionary.

Using None which is not a list.

Using 0 which is an integer, not a list.

The stack is used to store indices and should start empty, so an empty list [] is correct.

2fill in blank

medium

Complete the code to append the current index i to the stack.

DSA Python

stack.[1](i)

Drag options to blanks, or click blank then click option'

Ainsert

Bremove

Cpop

Dappend

Attempts:

3 left

💡 Hint

Common Mistakes

Using pop which removes an element instead of adding.

Using insert which requires an index and is not typical for stack push.

Using remove which deletes a specific value.

To add an element to the end of a list (stack), use the append method.

3fill in blank

hard

Fix the error in the condition to check if the stack is not empty.

DSA Python

while stack and heights[i] < heights[[1]]:

Drag options to blanks, or click blank then click option'

Ai

Bstack[-1]

Cstack[0]

D-i

Attempts:

3 left

💡 Hint

Common Mistakes

Using stack[0] which is the bottom of the stack.

Using i which is the current index, not the top of the stack.

Using -i which is invalid indexing.

To get the last element in the stack, use stack[-1]. This checks the height at the top index.

4fill in blank

hard

Fill both blanks to calculate the width correctly when popping from the stack.

DSA Python

width = i - [1] - [2]

Drag options to blanks, or click blank then click option'

Astack.pop()

Bstack[-1]

C1

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using stack.pop() inside width calculation which removes an element again.

Using 0 instead of 1 which gives wrong width.

Using stack[0] which is bottom of stack, not top.

The width is calculated as the difference between current index i and the index at the new top of the stack stack[-1], minus 1.

5fill in blank

hard

Fill both blanks to update max_area correctly inside the loop.

DSA Python

max_area = max(max_area, heights[[1]] * [2])

Drag options to blanks, or click blank then click option'

Astack.pop()

Bwidth

Cstack[-1]

Di

Attempts:

3 left

💡 Hint

Common Mistakes

Using stack[-1] instead of popping for height.

Using i instead of width for multiplication.

Not updating max_area with max function.

We pop the top index to get the height, multiply by the width calculated, and update max_area with the maximum value.