Lifesight Software Developer Interview Questions and Answers

Round duration - 120 minutes
Round difficulty - Medium

Evening test around 5
Platform :- SHL
Environment was amazing

Q1. 
Subtree of Another Tree Problem Statement
Given two binary trees, T and S, determine whether S is a subtree of T. The tree S should have the same structure and node values as a subtree of T.
Explanation:
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Ans. 
Given two binary trees T and S, determine if S is a subtree of T with the same structure and node values.
• Check if the second tree is a subtree of the first tree by comparing their structures and node values.

• Use a recursive approach to traverse both trees and check for equality.

• Handle cases where one tree is null or the values do not match.

• Return true if S is a subtree of T, false otherwise.
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Q2. 
Search in a Row-wise and Column-wise Sorted Matrix Problem Statement
You are given an N * N matrix of integers where each row and each column is sorted in increasing order. Your task is to find the positi...read more
Ans. 
Given a sorted N*N matrix, find the position of a target integer X.
• Iterate over each row and column to find the target integer X

• Utilize the sorted nature of the matrix to optimize the search process

• Return the position of X if found, else return -1 -1
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Round duration - 60 minutes
Round difficulty - Medium

1 Hour 
Afternoon

Q1. 
Intersection of Linked List Problem
You are provided with two singly linked lists containing integers, where both lists converge at some node belonging to a third linked list.
Your task is to determine t...read more
Ans. 
Find the node where two linked lists merge, return -1 if no merging occurs.
• Traverse both lists to find their lengths and the difference in lengths

• Move the pointer of the longer list by the difference in lengths

• Traverse both lists simultaneously until they meet at the merging point
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Q2. 
Problem: Pair Sum in a Binary Search Tree
Given a Binary Search Tree (BST) and an integer 'S', your task is to find all pairs of nodes within the BST that total to 'S' and return these pairs. If no such p...read more
Ans. 
Find pairs of nodes in a BST that sum up to a given value 'S'.
• Traverse the BST in-order to get a sorted list of nodes.

• Use two pointers approach to find pairs with sum 'S'.

• Keep track of visited nodes to avoid using the same node twice in a pair.
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Round duration - 60 minutes
Round difficulty - Medium

Online Round held on Chime

Q1. 
Is Binary Heap Tree Problem Statement
You are given a binary tree of integers. Your task is to determine if it is a binary heap tree or not.
Input:
The first line of input contains an integer ‘T’ denoti...read more
Ans. 
Determine if a given binary tree is a binary heap tree or not based on certain properties.
• Check if the binary tree is a complete binary tree where every level, except the last level, is completely filled and the last level is as far left as possible.

• Ensure that every parent node is greater than all its children nodes, forming a max-heap.

• If any node does not have a left or right child, it should be represented as -1 in ...read more
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Q2. 
Edit Distance Problem Statement
Given two strings S and T with lengths N and M respectively, your task is to find the "Edit Distance" between these strings.
The Edit Distance is defined as the minimum nu...read more
Ans. 
The task is to find the minimum number of operations required to convert one string into another using delete, replace, and insert operations.
• Use dynamic programming to solve the problem efficiently.

• Create a 2D array to store the edit distances between substrings of the two input strings.

• Fill up the array based on the minimum of three possible operations: insert, delete, or replace.

• The final answer will be the value at...read more
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Round duration - 90 Miinutes
Round difficulty - Medium

First round had MCQ + 2 coding questions. It was held in morning around 11 am. It was held on campus.

Q1. 
Robot Delivery Path Problem
You are tasked with directing a robot from the top-left corner of an N*N matrix to a specified point (x, y), delivering a parcel. The robot is restricted to move only on flat a...read more
Ans. 
Determine if a robot can reach a specified destination in a matrix by moving only downwards or rightwards.
• Start at (0,0) and move towards the destination (x, y) only downwards or rightwards.

• Check if the path is clear (1) and avoid obstacles (0) while staying within matrix boundaries.

• Return true if the robot can reach the destination, false otherwise.

• Example: For input matrix [[1, 0, 1], [1, 1, 1], [1, 1, 5]] with desti...read more
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Q2. 
Unique Element in Array
Given an arbitrary array arr consisting of N non-negative integers where every element appears thrice except for one. Your task is to find the element in the array that appears onl...read more
Ans. 
Find the unique element in an array where every element appears thrice except for one.
• Use XOR operation to find the unique element.

• Iterate through the array and XOR each element to find the unique element.

• The XOR operation cancels out elements that appear thrice, leaving only the unique element.

• Example: arr = [2, 2, 3, 2], XOR of all elements = 3.

• Example: arr = [0, 1, 0, 1, 0, 1, 99], XOR of all elements = 99.
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Round duration - 90 Minutes
Round difficulty - Medium

Second Round was held in morning around 10-11 am. There was one interviewer working on his laptop. Interviewer was really helpful and first offered me water and then for a bit talked about himself.

Q1. 
BST Iterator Problem Statement
You are tasked with implementing a class BSTIterator, which is designed to traverse a Binary Search Tree (BST) in the inorder manner. The class must support the following op...read more
Ans. 
Implement a BSTIterator class to traverse a Binary Search Tree in inorder manner.
• Implement a constructor to initialize the iterator with the root of the BST.

• Implement next() and hasNext() methods to traverse the BST in inorder.

• Implement prev() and hasPrev() methods to access the previous element in the inorder traversal.

• Use level-order traversal format to represent the tree input.

• Output the inorder traversal of the bin...read more
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Q2. 
Distance Between Two Nodes in a Binary Tree
Given a binary tree and the values of two distinct nodes, determine the distance between these two nodes in the tree. The distance is defined as the minimum num...read more
Ans. 
Calculate the distance between two nodes in a binary tree.
• Traverse the tree to find the paths from the root to each node

• Find the lowest common ancestor of the two nodes

• Calculate the distance by adding the distances from the LCA to each node
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