Infix to Postfix Conversion Using Stack in DSA Python - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to push an operator onto the stack.

DSA Python

stack.[1](ch)

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

Apop

Bpush

Cappend

Dinsert

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'push' which is not a Python list method.

In Python, to add an element to the end of a list (used as a stack), we use append.

2fill in blank

medium

Complete the code to pop the top element from the stack.

DSA Python

top = stack.[1]()

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

Adelete

Bpop

Cremove

Dappend

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'remove' which removes by value, not by position.

To remove and get the last item from a list (stack), use pop().

3fill in blank

hard

Fix the error in the precedence function to return correct precedence for '+' operator.

DSA Python

if op == '[1]':
    return 1

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

A+

B-

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing '+' with '-' or '*'.

The '+' operator has precedence 1 in this function.

4fill in blank

hard

Fill both blanks to correctly check operator precedence and decide stack pop.

DSA Python

while stack and precedence(stack[-1]) [1] precedence(ch):
    postfix += stack.[2]()

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

A>=

B<=

Cpop

Dappend

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<=' instead of '>='.

Using 'append' instead of 'pop'.

We pop from stack while top has higher or equal precedence, so use '>=' and pop().

5fill in blank

hard

Fill all three blanks to correctly handle closing parenthesis in the stack.

DSA Python

while stack and stack[-1] != [1]:
    postfix += stack.[2]()
stack.[3]()  # Remove '('

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

A'('

Bpop

Cappend

D')'

Attempts:

3 left

💡 Hint

Common Mistakes

Using ')' instead of '(' for comparison.

Using append instead of pop.

We pop until '(' is found, then pop '(' itself. So use '(' for comparison and pop() to remove.