L2 · Working engineerObject-oriented Python~4 min · 3 tests#73

Method Overriding and super()

Override a parent method in a Python subclass and still call the parent version with super(). Polymorphism explained with an Animal/Dog example.

The problem

Animal.speak() returns "Some sound".
Dog(Animal) overrides speak() to return "Bark".
Dog.both() returns a tuple (parent's speak, own speak) using super() — ("Some sound", "Bark").

Examples

Example 1

Input

(Animal().speak(), Dog().speak())

Expected output

('Some sound', 'Bark')

Example 2
Input
```
Dog().both()
```
Expected output
```
('Some sound', 'Bark')
```

+ 1 hidden test on Submit — polymorphism.

Edge cases to ask about

Calling the parent version
Mixed collections

Hints

0/3

How an interviewer scores this

0/9

1. Understand the problemRestate it, ask about edge cases and input size.
2. Write a brute-force solutionCorrect first, clever later.
3. Get the correct outputautoAll visible examples pass.
4. Analyse time complexityautoCommit to a Big-O in the Complexity Lab.
5. Analyse space complexityautoExtra memory, not the input.
6. Identify the bottleneckautoMeasure your code — where does it bend?
7. OptimiseUsually: a set or dict instead of a scan.
8. Explain why it worksSay it out loud to Solvi.
9. Test the edge casesautoSubmit passes every hidden test.

Python 3.13 · Dog

class Animal:
    def speak(self):
        return "Some sound"


class Dog(Animal):
    def speak(self):
        pass

    def both(self):
        pass

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Complexity Lab

What does this cost as n grows?

Interviewers score the analysis as much as the code. Commit to an answer first — then check it, and read why.

Time complexity of the optimal solution

Space complexity (extra memory)

Pick both to reveal the answer.

From brute force to optimal

The progression an interviewer wants to hear, one step at a time.

Approach	Time	Space	Idea
Override + super()	O(1)	O(1)	super() delegates to the next class in the MRO.

Walkthrough of the optimal approach (try it yourself first)

Defining speak in Dog overrides Animal's version: self.speak() on a Dog finds Dog's method first. super().speak() skips to the next class in the MRO, so you can extend rather than replace parent behaviour.

Calling the same method on a mixed list of Animals and Dogs and getting the right behaviour for each is polymorphism.

Complexity: O(1) time, O(1) space. Constant-time method dispatch.

Reveal the reference solution

class Animal:
    def speak(self):
        return "Some sound"


class Dog(Animal):
    def speak(self):
        return "Bark"

    def both(self):
        return super().speak(), self.speak()

Follow-ups interviewers ask

Call super().init correctly in a subclass constructor.
What does super() do with multiple inheritance?

Frequently asked interview questions

Core interview concepts, complexities, and follow-ups scored by hiring teams.

What is the time complexity of Method Overriding and super() in Python?

The optimal solution runs in O(1) time and O(1) auxiliary space. Constant-time method dispatch.

What follow-up questions do interviewers ask about Method Overriding and super()?

Call super().__init__ correctly in a subclass constructor. What does super() do with multiple inheritance?