Min Stack Design in DSA Python - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to push an element onto the stack.

DSA Python

def push(self, val):
    self.stack.append([1])

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

Aval

Bself.min_stack[-1]

Cself.stack[-1]

Dmin(val)

Attempts:

3 left

💡 Hint

Common Mistakes

Using self.min_stack[-1] instead of val.

Trying to call min(val) which is incorrect.

Using self.stack[-1] which is the last element, not the new one.

We push the given value 'val' onto the main stack.

2fill in blank

medium

Complete the code to update the min_stack when pushing a new value.

DSA Python

def push(self, val):
    self.stack.append(val)
    if not self.min_stack or val [1] self.min_stack[-1]:
        self.min_stack.append(val)
    else:
        self.min_stack.append(self.min_stack[-1])

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

A>

B>=

C==

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' instead of '<=' which breaks min tracking.

Using '==' which misses smaller values.

Using '>=' which is incorrect for minimum.

We add val to min_stack if it is smaller or equal to the current minimum.

3fill in blank

hard

Fix the error in the pop method to correctly remove elements from both stacks.

DSA Python

def pop(self):
    if self.stack:
        self.stack.pop()
        [1]

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

Aself.min_stack.push()

Bself.min_stack.pop()

Cself.min_stack.append()

Dself.min_stack.remove()

Attempts:

3 left

💡 Hint

Common Mistakes

Using append() instead of pop().

Using push() which is not a list method.

Using remove() which removes by value, not last element.

We must pop from min_stack to keep stacks in sync.

4fill in blank

hard

Fill both blanks to return the current minimum element from the stack.

DSA Python

def getMin(self):
    if self.min_stack:
        return self.min_stack[1][2]

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

A[-1]

B[0]

C.pop()

D.append()

Attempts:

3 left

💡 Hint

Common Mistakes

Using [0] which returns the first element, not the minimum.

Using .pop() which removes the element.

Using .append() which adds an element.

We return the last element of min_stack which is the current minimum.

5fill in blank

hard

Fill all three blanks to complete the MinStack class with push, pop, and getMin methods.

DSA Python

class MinStack:
    def __init__(self):
        self.stack = []
        self.min_stack = []

    def push(self, val):
        self.stack.append(val)
        if not self.min_stack or val [1] self.min_stack[-1]:
            self.min_stack.append(val)
        else:
            self.min_stack.append(self.min_stack[-1])

    def pop(self):
        if self.stack:
            self.stack.pop()
            self.min_stack.[2]()

    def getMin(self):
        if self.min_stack:
            return self.min_stack[3]

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

A<=

Bpop

C[-1]

Dappend

Attempts:

3 left

💡 Hint

Common Mistakes

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

Using append() instead of pop() in pop method.

Using [0] or pop() in getMin which removes element.

The push uses '<=' to update min_stack, pop calls pop(), and getMin returns last element.