Coding practice

Coding problems candidates reported from company coding rounds (memory-based), written up with our own examples and hints. A live code editor with test cases is coming soon.

Second largest number Easy · Arrays · Infosys (2022–25), Accenture, Cognizant GenC, LTIMindtree
Rotate an array Easy · Arrays · Infosys (2021–25), Accenture
Find the missing number Easy · Arrays · Infosys (2021–26), Wipro Elite NTH, Accenture, Cognizant GenC, Deloitte (2025)
Move zeros to the end Easy · Arrays · HCLTech, Deloitte
Even numbers first Easy · Arrays · Wipro Elite NTH
Count the record-breakers Easy · Arrays · TCS NQT (Sep 2023)
Peak guests on board Easy · Arrays · TCS NQT (Sep 2023)
First colour with an odd count Easy · Arrays · TCS NQT (Sep 2023)
Row with the most 1s Easy · Arrays · TCS NQT (Sep 2023)
Maximum subarray sum Medium · Arrays · Infosys (SP / DSE), Cognizant GenC
Greatest element on the right Easy · Arrays · Cognizant GenC (GenC Next)
Middle equals the sum of its neighbours Easy · Arrays · Cognizant GenC
Merge two sorted arrays Easy · Sorting and searching · LTIMindtree (2025), Cognizant GenC
Subarrays with sum K Medium · Arrays · HCLTech
Subarrays with an odd sum Medium · Arrays · Deloitte
Count values close to a number Easy · Arrays · Accenture (Aug 2022), Deloitte
Longest decreasing run Easy · Arrays · Capgemini (2026 batch)
Best sum of pair minimums Easy · Sorting and searching · Capgemini (2026 batch)
Sum of both diagonals Easy · Arrays · Infosys (2022–24), Wipro Elite NTH
Houses needed to feed the rats Easy · Arrays · Accenture (Aug 2022)
Odd count minus even count Easy · Arrays · Tech Mahindra (2024)
Pen switches Easy · Arrays · Cognizant GenC
Longest increasing subsequence Medium · Dynamic programming · Infosys (DSE / SP, 2021–26)
Fewest coins Hard · Dynamic programming · Infosys (DSE / SP, 2021–26)
Palindrome check Easy · Strings · Infosys (2021–26), Accenture, Cognizant GenC, Deloitte (Feb 2026), LTIMindtree
Count vowels Easy · Strings · Infosys (2021–23), Accenture, Cognizant GenC
Character frequency Easy · Strings
Reverse the words Easy · Strings · Wipro Elite NTH, Accenture, HCLTech
First non-repeating character Easy · Strings · Wipro Elite NTH, Infosys (2021–25), Accenture
Anagram check Easy · Strings · Infosys (2021–25), Accenture
Balanced brackets Medium · Strings · Infosys (2021–26), HCLTech
Longest substring without repeats Medium · Strings · Infosys (DSE / SP, 2021–26), Tech Mahindra, LTIMindtree
Typing with backspace Easy · Strings · TCS NQT
Pangram check Easy · Strings · TCS NQT
Longest sentence Easy · Strings · TCS NQT
Shift cipher for letters and digits Easy · Strings · TCS NQT
Stars versus hashes Easy · Strings · TCS NQT (Sep 2023)
Password checker Easy · Strings · Accenture (Aug 2022; 2025–26)
Evaluate a binary operation string Easy · Strings · Accenture (Aug 2022)
Move hyphens to the front Easy · Strings · Accenture (Aug 2021)
Count non-repeated characters Easy · Strings · Tech Mahindra (2024)
Longest balanced binary substring Medium · Strings · Capgemini (2026 batch)
Prime string check Easy · Strings · Capgemini (2026 batch)
Compress repeated letters Easy · Strings · Capgemini
Reverse a string Easy · Strings · Tech Mahindra, LTIMindtree, Cognizant GenC
Longest common subsequence Medium · Dynamic programming · LTIMindtree
Primes in a range Easy · Maths · LTIMindtree, Tech Mahindra
Two-wheelers and four-wheelers Easy · Maths · TCS NQT (Sep 2023)
Armstrong number Easy · Maths · HCLTech, Accenture
Power of two Easy · Maths · Infosys (2022–25)
Difference of sums Easy · Maths · Accenture (Aug 2022), Deloitte
Count the carries Easy · Maths · Accenture (Aug 2021)
Decimal to base B Easy · Maths · Accenture (Aug 2022)
Toggle the bits Easy · Bits · Deloitte
Numbers with K set bits Medium · Bits · Deloitte
Set bits and their positions Easy · Bits · Tech Mahindra (2024)
Remove one digit to get the largest number Easy · Strings · Infosys (DSE / SP, 2023–26)
Buzz number Easy · Maths · Cognizant GenC