Paytm (One97 Communications Limited) interview experience Real time questions & tips from candidates to crack your interview

SDE - Intern

Paytm (One97 Communications Limited)
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2 rounds | 4 Coding problems

Interview preparation journey

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Preparation
Duration: 6 months
Topics: Data Structures, Pointers, OOPS, System Design, Algorithms, Dynamic Programming, OS, DBMS
Tip
Tip

Tip 1 - Practice Atleast 250 Questions from geeks from geeks and coding ninjas
Tip 2 - Ex- Do atleast 2 good projects

Application process
Where: Campus
Eligibility: Above 7 CGPA
Resume Tip
Resume tip

Tip 1 : Have some projects on resume.
Tip 2 : Do not put false things on resume and be confident.

Interview rounds

01
Round
Easy
Online Coding Test
Duration70 minutes
Interview date1 Dec 2019
Coding problem2

3 Coding Question 

1st Question : Finger counting game 
2nd Question : Count number of triplets with product equal to given number 
3rd Question : K’th Smallest/Largest Element in Unsorted Array

1. 3Sum

Moderate
15m average time
85% success
0/80
Asked in companies
CiscoMathworksSamsung

You are given an array/list ARR consisting of N integers. Your task is to find all the distinct triplets present in the array which adds up to a given number K.

An array is said to have a triplet {ARR[i], ARR[j], ARR[k]} with sum = 'K' if there exists three indices i, j and k such that i!=j, j!=k and i!=j and ARR[i] + ARR[j] + ARR[k] = 'K'.

Note:
1. You can return the list of values in any order. For example, if a valid triplet is {1, 2, -3}, then {2, -3, 1}, {-3, 2, 1} etc is also valid triplet. Also, the ordering of different triplets can be random i.e if there are more than one valid triplets, you can return them in any order.
2. The elements in the array need not be distinct.
3. If no such triplet is present in the array, then return an empty list, and the output printed for such a test case will be "-1".
Problem approach

Store all the elements in a hash_map with their index.
Consider all pairs(i, j) and check the following: 
If (arr[i]*arr[j] !=0 && (m % arr[i]*arr[j]) == 0), If yes, then search for ( m / (arr[i]*arr[j]) in the map.
Also check m / (arr[i]*arr[j]) is not equal to arr[i] and arr[j].
Also, check that the current triplet is not counted previously by using the index stored in the map.
If all the above conditions are satisfied, then increment the count.
Return count.

Try solving now

2. Kth smallest element in an unsorted array

Moderate
15m average time
85% success
0/80
Asked in companies
Paytm (One97 Communications Limited)DelhiveryAmazon

Given an unsorted array ‘arr’ of distinct integers and an integer ‘k’, your task is to find the ‘k-th’ smallest element in the array.

Example:
n = 5, k = 2 and arr[] = {6, 5, 4, 8, 7}
The array elements in sorted order are [4, 5, 6, 7, 8]. The ‘2-nd’ smallest element in the array is 5, so the answer is 5.
Note:
1. Don’t print anything. Return the value of ‘k-th’ smallest element.
2. ‘k’ is a positive integer and not greater than the size of the array.
3. The array ‘arr’ is unsorted, and all the elements of the array are distinct.
Problem approach

The idea is to randomly pick a pivot element. To implement randomized partition, we use a random function, rand() to generate index between l and r, swap the element at randomly generated index with the last element, and finally call the standard partition process which uses last element as pivot.

Try solving now
02
Round
Medium
Face to Face
Duration60 minutes
Interview date3 Dec 2019
Coding problem2

The interviewer was very friendly. He asked me to introduce myself 

Then he asked me some question Find GCD of two numbers 
Just approach 

At this point he asked me difference between process and thread.
Top view of binary tree 
First we discussed approach He gave m test case where my approach is failing and gave me time to think and i come up with correct approach and then he asked me to write full code on pen-paper and i did it.

1. Greatest Common Divisor

Easy
15m average time
85% success
0/40
Asked in companies
Paytm (One97 Communications Limited)OracleGoldman Sachs

You are given two numbers, ‘X’ and ‘Y’. Your task is to find the greatest common divisor of the given two numbers.

The Greatest Common Divisor of any two integers is the largest number that divides both integers.

For Example:
You are given ‘X’ as 20 and ‘Y’ as 15. The greatest common divisor, which divides both 15 and 20, is 5. Hence the answer is 5.
Problem approach

For finding GCD of two numbers we will first find the minimum of the two numbers and then find the highest common factor of that minimum which is also the factor of the other number.

Try solving now

2. Top View Of Binary Tree

Moderate
25m average time
70% success
0/80
Asked in companies
Thought WorksSamsung R&D InstituteMicrosoft

You are given a Binary Tree of 'n' nodes.


The Top view of the binary tree is the set of nodes visible when we see the tree from the top.


Find the top view of the given binary tree, from left to right.


Example :
Input: Let the binary tree be:

Example

Output: [10, 4, 2, 1, 3, 6]

Explanation: Consider the vertical lines in the figure. The top view contains the topmost node from each vertical line.
Problem approach

The idea is to do something similar to vertical Order Traversal. Like vertical Order Traversal, we need to put nodes of same horizontal distance together. We do a level order traversal so that the topmost node at a horizontal node is visited before any other node of same horizontal distance below it. Hashing is used to check if a node at given horizontal distance is seen or not.

Try solving now

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