Coupang Interview Questions and Answers

Round duration - 90 minutes
Round difficulty - Easy

The test was of moderate level, the coding question was easy if all the boundary questions were properly considered.

Q1. 
Largest Prime Factor Problem Statement
You are given a positive integer n. Your task is to identify the largest prime factor of this given positive integer.
If there is no prime factor for a given intege...read more
Ans. 
Identify the largest prime factor of a given positive integer.
• Iterate from 2 to sqrt(n) to find prime factors

• Check if each factor is prime and update largest prime factor

• If no prime factor found, output -1
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Q2. 
First Missing Positive Problem Statement
You are provided with an integer array ARR of length 'N'. Your objective is to determine the first missing positive integer using linear time and constant space. T...read more
Ans. 
Find the smallest positive integer missing from an array of integers.
• Iterate through the array and mark positive integers as visited using index as a reference.

• After marking, iterate again to find the first unmarked index which represents the missing positive integer.

• Handle edge cases like duplicates and negative numbers appropriately.

• Example: For input [3, 4, -1, 1], the output should be 2.
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Round duration - 60 minutes
Round difficulty - Easy

The interviewer was friendly and he was interested in the implementation first and then the code.
Tips: Be thorough with various implementations and why they are in practice. Try to know the logic behind each implementation.

Q1. 
Binary Array Sorting Problem Statement
You are provided with a binary array, i.e., an array containing only 0s and 1s. Your task is to sort this binary array and return it after sorting.
Input:
 The fir...read more
Ans. 
Yes, the binary array can be sorted in linear time and constant space using a single traversal.
• Use two pointers approach to swap 0s to the left and 1s to the right.

• Maintain two pointers, one for 0s and one for 1s, and iterate through the array once.

• Example: Input array [1, 0, 1, 0, 1] will be sorted to [0, 0, 1, 1, 1] in a single traversal.
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Q2. What is polymorphism in object-oriented programming?
Ans. 
Polymorphism in OOP allows objects of different classes to be treated as objects of a common superclass.
• Polymorphism allows for flexibility and reusability in code.

• It enables a single interface to be used for different data types.

• Examples include method overriding and method overloading.
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Q3. What is operator overloading?
Ans. 
Operator overloading is the ability to redefine the behavior of operators for user-defined data types.
• Allows operators to be used with custom data types

• Can define custom behavior for operators like +, -, *, etc.

• Helps make code more readable and intuitive

• Example: Overloading the + operator for a custom Vector class to add two vectors
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Q4. What is the difference between method overloading and method overriding?
Ans. 
Method overloading is having multiple methods in the same class with the same name but different parameters. Method overriding is having a method in a subclass with the same name and parameters as a method in its superclass.
• Method overloading involves multiple methods with the same name but different parameters.

• Method overriding involves a subclass redefining a method from its superclass with the same name and paramete...read more
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Round duration - 45 minutes
Round difficulty - Easy

The interviewer was looking for a person interested in problem solving. He was looking forward for loud thinking.
Tips: If you don't know any answer, don't lose your cool. It is never necessary to answer all the questions in an interview. Be confident and think loud, so that if you are going the wrong way, the interviewer can assist you.

Round duration - 30 minutes
Round difficulty - Easy

This was the last round and just for formality. The interviewers were looking for a person who would fit in their working culture.
Tips: Be confident and always have a smile on your face. If you are selected for the HR interview, then there is a 90% chance that you would be selected.