Data Structures
Implement a rate limiter
shouldAllowRequest() that returns true if the incoming requests have arrived at a rate less than or equal to specified rate,
Bit Manipulation, String Manipulation
Boolean String Value
Given a string consisting of only 0, 1, A, B, C where A = AND B = OR C =
Algorithms, Math Problems, String Manipulation
Print String Permutations
How will you print all permutations of characters in a string? 2026 Update: String Permutations — Three Approaches and the
Algorithms, Dynamic Programming, String Manipulation
Longest palindrome in a string
Write a function to find the longest palindrome in a string. 2026 Update: Longest Palindrome — Character Frequency Approach There
Dynamic Programming, Math Problems
Prime number problem
You need to a number of floors in a building. There are 68 floors (numbered 1 to 64). Conditions: 1.
Data Structures, System Design
Missing country code
Missing Country Code Imagine you get a data set from a client that contains addresses from 150 countries all around
Math Problems
Prime number problem
A man has to buy 7 floors in a building. Numbered floor 1 to 68. Conditions: 1. He cannot buy