ThoughtWorks Software Developer Interview Questions, Process, and Tips

Round duration - 60 minutes
Round difficulty - Medium

Mcq + Data structures questions

Q1. 
Maximum Sum Subarray Problem Statement
Given an array of integers, find the maximum sum of any contiguous subarray within the array.
Example:
Input:
array = [34, -50, 42, 14, -5, 86]
Output:
137
Exp...read more
Ans. Brute Force Approach
1. Create a nested loop. The outer loop will go from i = 0 to i = n - k. This will cover the starting indices of all k-subarrays
2. The inner loop will go from j = i to j = i + k - 1. This will cover all the elements of the k-subarray starting from index i
3. Keep track of the maximum element in the inner loop and print it.
Space Complexity: O(1)Explanation:
O(1) because the extra space being used (looping vari...read more
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Round duration - 70 minutes
Round difficulty - Medium

Standard System Design round

Q1. Design a Doctor Appointment System and provide some test cases.
Ans. 
Tip 1 : Implement using OOPs 
Tip 2 : Try to tell your approach to the interviewer as much as you can side by side
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Round duration - 90 minutes
Round difficulty - Medium

Interview of DSA + OOPS + Databse(SQL query) + Operating System

Q1. 
Left View of a Binary Tree
Given a binary tree, your task is to print the left view of the tree. The left view of a binary tree contains the nodes visible when the tree is viewed from the left side.
Inpu...read more
Ans. Recursive Approach
This problem can be solved through recursion.We will maintain max_level variable which will keep track of maxLevel and will pass current level in recursion as argument. Whenever we see a node whose current level is more than maxLevel then we will print that node as that will be first node for that current level. Also update maxLevel with current level.
Space Complexity: O(n)Explanation:
O(N), where ‘N’...read more
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Q2. What is the difference between CHAR and VARCHAR2 data types in SQL?
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Q3. What are the various types of constructors in C++?
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Q4. What is the difference between overloading and overriding?
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Round duration - 60 minutes
Round difficulty - Easy

Hr round - normal hr questions + situational 

Thoughtworks community discussion

Q1. Why should we hire you?
Ans. 
Tip 1 : Read all Thoughtworks community page and be honest

Tip 2 : Be open-minded and answer whatever you are thinking, in these rounds I feel it is important to have opinion.

Tip 3 : The cross-questioning can go intense sometimes, think before you speak.
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DSA

About Social changes

Q1. Tell me about yourself.
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Q2. Very basic questions
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Round duration - 90 minutes
Round difficulty - Medium

We were supposed to give test in any time between 3 PM to 9 PM.

Q1. 
Total Unique Paths Problem Statement
You are located at point ‘A’, the top-left corner of an M x N matrix, and your target is point ‘B’, the bottom-right corner of the same matrix. Your task is to calcula...read more
Ans. Recursive Approach
We can easily count the total number of paths by making a recursive algorithm.
 
The steps are as follows:
 
1. We are given a function UNIQUEPATHS(), which takes two integers ‘M’ and ‘N’ as parameters and returns a single integer. This will be the definition of our recursive function too.
2. As our base condition, we will check if our number of rows (‘M’) or a number of columns (‘N’) is equal to 1. If...read more
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Q2. 
Subtree Node Count Problem
We are provided with a tree containing 'N' nodes, numbered from 0 to N-1. The objective is to determine the total number of nodes within each subtree of the provided tree. Speci...read more
Ans. DFS
An easy way to solve this problem will be to run a modified DFS over the given tree. 
1. Create the output array, “arr” of size ‘N’, where ‘N’ is the number of nodes in the tree.
2. Call the DFS function with source as 0, parent of source as -1(root has no parent) and the given adjacency list.
3. In the DFS function, initialize the count of nodes in the subtree rooted at src with 1.
4. Then, iterate through all the immediate c...read more
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Round duration - 120 minutes
Round difficulty - Medium

Pair Programming Interview( this round is similar to machine coding round) it started around 11 AM

Focus Areas: Problem solving and implementation of extensions.

The pair coding round is focused on OOPS concepts. You are paired with a TWer for this round. They let you code first for an hour and in the next hour they review your code and suggest changes which would improve the code structure, readability and make it modular and reusable and functional.
 

Q1. 
River Crossing: Help Ninja Cross Over
Ninja stands at the start of a wooden bridge over a river. Some segments of the bridge are damaged. The undamaged segments, marked as 'safe', are listed in an array S...read more
Ans. Recursion
Complete Algorithm:
• First of all, we will make a HashMap say ‘MY_MAP’ to store safe units where the key will be ‘SAFE[i]’ and the value will be ‘i’.
• We will make a helper recursive function named ‘SOLVE’ which will receive 4 parameters ‘SAFE’, ‘MY_MAP’, index of current unit ‘INDEX’ and size of previous jump ‘X’.
• Base Case:
  • If ‘INDEX’ is equal to last safe unit:
    • Return true.
• Recursive Calls:
  • Now we have three possibl...read more
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Round duration - 120 minutes
Round difficulty - Medium

Students who were shortlisted from Pair Programming round was selected for this round around 3 PM. In this round there were two interviewer.

Q1. 
Middle of a Linked List
You are given the head node of a singly linked list. Your task is to return a pointer pointing to the middle of the linked list.
If there is an odd number of elements, return the ...read more
Ans. Count Nodes Approach
• If we want to know the midpoint of any linked list, it is very easy to do so if we know the number of elements in the linked list.
• We take a pointer ‘p’ and use it to traverse the linked list and until we find NULL we increment a variable ‘count’ to count the number of elements in the linked list.
• We then divide the number of elements by 2 to get the position of the middle element of the linked list.
• F...read more
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