Reverse a doubly linked list
How can you reverse a double linked list? 2026 Update: Reversing a Doubly Linked List — Full Implementation Reversing a […]
Algorithms, Data Structures
Arrays, Data Structures
Sum Up a Pair in Array
Can you find a pair in array that will sum up to particular number? 2026 Update: Two Sum — The
Coding Interview Questions
paradox dragon
I met three dragons. One always tells the truth, other one always lies and the last one alternates between lie
Algorithms, Arrays, Data Structures
Right Rotate an array by k elements
An array of elements is given arr arr is of length n Right rotate array by k elements Time complexity
Coding Interview Questions
Can you forecast weather?
It is raining at midnight – will we have sunny weather in 72 hours? 2026 Update: Weather Forecasting — Machine
Coding Interview Questions
Half full
A half is a third of it. What is it? 2026 Update: The Half-Full Glass — Estimation and Fermi Problems
Coding Interview Questions
Upside down years
When was the last year that looked the same upside down? (1961) 2026 Update: Strobogrammatic Numbers — Rotation Invariant Digits
Coding Interview Questions
Good (or really bad) icebreaker question
A book costs $1 plus half its price. How much does it cost? 2026 Update: The Interview Icebreaker — How
Data Structures, Dynamic Programming
How many floors can an egg be dropped without breaking?
Question: You have two identical eggs. Standing in front of a 100 floor building, you wonder what is the maximum
Brain Teasers, Data Structures
Building a Stack with a getMax() function
Suppose you had a Stack class. Write a new class MaxStack which, in addition to push() and pop(), has a
Logic Puzzles
Getting a fair result with an unfair coin
How can you get a fair coin toss if someone hands you a coin that is weighted to come up
Bit Manipulation, Google Interview Questions
Storing 1 million phone numbers
What is the most efficient way, memory-wise, to store 1 million phone numbers? Apparently this is an interview question at
Algorithms, Arrays, Brain Teasers, Data Structures, String Manipulation
Reverse a String
A typical programming interview question is “reverse a string, in place”. if you understand pointers, the solution is simple. even
Brain Teasers, Logic Puzzles
100 Doors in a Row
Problem: you have 100 doors in a row that are all initially closed. you make 100 passes by the doors
Brain Teasers, Data Structures, Dynamic Programming, Logic Puzzles
Red Marbles, Blue Marbles
Problem: you have two jars, 50 red marbles, 50 blue marbles. you need to place all the marbles into the