HCLTech

Global IT services and consulting company.

4 Rounds ~21 Days Medium
Start Mock Interview

The Interview Loop

Recruiter Screen (30 min)

Standard fit check, behavioral questions, and resume overview.

Technical Loop (3-4 Rounds)

Deep dive into domain knowledge, coding, and system design.

Interview Question Bank

Backend Engineer • Coding • easy

Given an array of integers and an integer target, return indices of the two numbers such that they add up to target. Can you do it in O(n) time complexity?

#Arrays #Hash Table
Practice
Backend Engineer • Coding • medium

Given the root of a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom.

#Binary Tree #Breadth-First Search #Depth-First Search
Practice
Backend Engineer • Coding • medium

Given an integer array nums and an integer k, return the k most frequent elements. You may return the answer in any order.

#Heap #Hash Table #Bucket Sort
Practice
Backend Engineer • Coding • hard

Given the head of a linked list, reverse the nodes of the list k at a time, and return the modified list.

#Linked List #Recursion
Practice
Backend Engineer • Coding • medium

Given an array of intervals where intervals[i] = [starti, endi], merge all overlapping intervals, and return an array of the non-overlapping intervals.

#Arrays #Sorting
Practice
Backend Engineer • Coding • medium

Find the length of the longest substring without repeating characters in a given string.

#Strings #Sliding Window
Practice
Data Engineer • Coding • easy

Write a Python function to check if a given string is a valid palindrome, ignoring special characters and case.

#Python #Strings #Two Pointers
Practice
Data Engineer • Coding • medium

Write a Python generator function to read a massive 50GB log file line by line without loading the entire file into memory.

#Python #Generators #File I/O
Practice
Data Engineer • Coding • medium

Given a complex nested JSON object (represented as a Python dictionary), write a recursive Python function to flatten it into a single-level dictionary.

#Python #Recursion #JSON
Practice
Data Engineer • Coding • easy

Write a Python function to find the first non-repeating character in a string. Return its index or -1 if it doesn't exist.

#Python #Hash Maps #Strings
Practice
Data Scientist • Coding • easy

Write a Python function to merge two sorted arrays into a single sorted array without using built-in sorting functions.

#Arrays #Two Pointers #Python
Practice
Data Scientist • Coding • easy

Implement a binary search algorithm in Python to find the index of a target value in a sorted array.

#Binary Search #Python #Data Structures
Practice
Data Scientist • Coding • easy

Write a Python function to reverse the words in a given string, maintaining the original spacing. How would you optimize this for a very large text corpus?

#Python #String Manipulation #Optimization
Practice
Data Scientist • Coding • medium

Given a string, write a Python function to find the length of the longest substring without repeating characters.

#Sliding Window #Hash Map #Python
Practice
Frontend Engineer • Coding • medium

Implement a function to flatten a deeply nested array without using Array.prototype.flat().

#Arrays #Recursion #Iteration
Practice
Full Stack Engineer • Coding • easy

Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

#Strings #Stack
Practice
Full Stack Engineer • Coding • medium

Merge two sorted arrays into a single sorted array without using extra space (O(1) space complexity).

#Arrays #Two Pointers #Sorting
Practice
Full Stack Engineer • Coding • easy

Detect if a linked list has a cycle in it.

#Linked List #Two Pointers
Practice
Full Stack Engineer • Coding • medium

Find the length of the longest substring without repeating characters.

#Strings #Sliding Window #Hash Table
Practice
Full Stack Engineer • Coding • medium

Perform a level order traversal of a binary tree and return the node values level by level.

#Trees #Breadth-First Search #Queue
Practice
Full Stack Engineer • Coding • easy

Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.

#Arrays #Hash Table
Practice
Full Stack Engineer • Coding • medium

Reverse a string without affecting the position of special characters.

#Strings #Two Pointers
Practice
Full Stack Engineer • Coding • easy

Find the first non-repeating character in a string and return its index. If it does not exist, return -1.

#Strings #Hash Table #Counting
Practice
Machine Learning Engineer • Coding • medium

Write a function to perform matrix multiplication from scratch using pure Python (no NumPy).

#Python #Math #Nested Loops
Practice
Machine Learning Engineer • Coding • medium

Given a list of dictionaries representing nested JSON data from a client API, write a script to flatten the dictionaries into a single-level dictionary.

#Python #Data Structures #Recursion
Practice
Machine Learning Engineer • Coding • medium

Implement a function to tokenize a string and remove stop words from scratch, without using external NLP libraries like NLTK or spaCy.

#Python #String Manipulation #NLP
Practice
Machine Learning Engineer • Coding • easy

Write a Python function to compute the moving average of a time series array given a specific window size.

#Python #Arrays #Time Series
Practice

Difficulty Radar

Based on recent AI-sourced data.

Meet Your Interviewers

The "Standard" Interviewer

Senior Engineer

Focuses on core competencies, system constraints, and clear communication.

Simulate

Unwritten Rules

Think Out Loud

Always explain your thought process before writing code or drawing architecture.

Practice Now