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 method getMax() which returns the largest item in the stack. Use your existing Stack class to store the stack’s contents. Don’t just use pop() to “dig” through your stack to find the max—do something that… Read More »

We are NY Tech asks: “How many unique areas of human knowledge have the right size of passionate users to make it as a Stack Exchange site?” Answer: 30,000.

Reverse a String

A typical programming interview question is “reverse a string, in place”. if you understand pointers, the solution is simple. even if you don’t, it can be accomplished using array indices. i usually ask candidates this question first, so they get the algorithm in their head. then i play dirty by asking them to reverse the… Read More »

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 starting with the first door every time. the first time through you visit every door and toggle the door (if the door is closed, you open it, if its open, you close it). the second… Read More »