Paytm Android Developer Interview Questions, Process, and Tips

Q1. DSA: Put zeroes to end in an array
Ans. 
Move all zeroes to the end of an array of strings.
• Iterate through the array and keep track of the count of zeroes encountered.

• Swap non-zero elements with the first zero encountered to move zeroes to the end.
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Q2. What is context? Type of context in android, what are the differences
Ans. 
Context in Android refers to the current state of the application. There are different types of context in Android with varying scopes and lifecycles.
• Context is an abstract class in Android that allows access to application-specific resources and classes.

• There are three main types of context in Android: Application Context, Activity Context, and Service Context.

• Application Context is tied to the lifecycle of the applic...read more
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Q1. Data structures and kotlin basics to advance
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Round duration - 45 Minutes
Round difficulty - Easy

Q1. BST Iterator
You are given a class named as BSTIterator that represents an iterator over inorder traversal of a binary search tree. You need to implement the following things as follows:
1. BSTIterator(No...read more
Ans. Tree flattening
• We need to implement two functions next() and hasNext(). The next() function will move the iterator to the right and return the next smaller element and the hasNext() function will return true if there exists the next smallest element else false.
• We can prepare a list that stores all the elements of the binary search tree in sorted order. We can do so by performing inorder traversal on the given binary se...read more
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Q2. Integer to Roman Numeral
Given an integer ‘N’, the task is to find its corresponding Roman numeral.
Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.
Symbol      Value
 ...read more
Ans. Brute Force
The idea is to convert each digit present at units, tens, hundreds and thousands places of the given number into roman numerals separately. Also, the conversion of some digits are a little bit different from other digits because these digits follow subtractive notation, i.e. 4 can be represented as “IV”, 9 can be represented as “IX” and so on.
 
Here is the algorithm :
 
1. Compare the given number with t...read more
Answered by CodingNinjas
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Round duration - 45 Minutes
Round difficulty - Medium

Q1. Cube Sum Pairs
You are given a positive integer N, and you have to find the number of ways to represent N as a sum of cubes of two integers(let’s say A and B), such that:
N = A^3 + B^3.
Note:
1. A sho...read more
Ans. Brute Solution
1. Maintain a counter which will count possible pairs (A, B).
2. Iterate over all possible ‘A’ values.
   • Possible ‘A’ values are in the range 1 to N.
3. For each ‘A’ value iterate over all possible values of ‘B’
   • Possible ‘B’ values are in the range 0 to N.
4. If ‘A’^3 + ‘B’^3 comes to be N, then increment the counter.
Space Complexity: O(1)Explanation:
O(1), as we are using constant extra memory.
Time Complexity: O(n^2)Explan...read more
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Q2. Colorful Knapsack
You are given 'N' stones labeled from 1 to 'N'. The 'i-th' stone has the weight W[i]. There are 'M' colors labeled by integers from 1 to 'M'. The &...read more
Ans. Recursive Approach
1. Create an array/list of size m+1. Let’s call this as weights, and add each weight of i’th color at the index i.
2. Call a recursive function with color 1 and having current weight as 0. The base case would be If we reach the (m+1)th color means we have exhausted the colors so return 0.
3. Now for i’th color, we will have a list of stones. We will try using each stone. We will use the stone if the
current weigh...read more
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Q3. Technical Question
Deep linking
scope storage 
why constraint layout(flat structure, lessrendering, responsive) 
how to handle run time permissions for aspecific version
Have you integrated payment ga...read more
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Round duration - 15 Minutes
Round difficulty - Easy

Q1. Basic HR Questions
Why paytm?
How is paytm different from its competition?
What changes you think can be made to make it better?
Can you take your stand for a decision if you believe its correct even when your...read more
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