Stack facts & stats

Question 1

If you push 1, then 2, then 3 onto an empty stack, what does the next pop return?

Accepted Answer

3. Pop removes the top item, which is the last one pushed: 3.

Question 2

What does a 'full-stack' developer work on?

Accepted Answer

Both the front end and the back end of an application. Full-stack developers handle the user-facing front end as well as the server-side back end.

Question 3

Which stack operation looks at the top item without removing it?

Accepted Answer

Peek. Peek (sometimes called top) returns the top item while leaving the stack unchanged.

Question 4

What commonly causes a 'stack overflow' error?

Accepted Answer

Recursion that never reaches a stopping case. Each function call adds a frame to the call stack; endless recursion keeps adding frames until space runs out.

Question 5

What is it called when a program tries to pop from an empty stack?

Accepted Answer

Stack underflow. Underflow means removing from an empty stack; overflow means adding beyond its capacity.

Question 6

Reverse Polish notation expressions like '3 4 +' are typically evaluated using what?

Accepted Answer

A stack. Numbers are pushed; each operator pops its operands, computes, and pushes the result back.

Question 7

Depth-first search of a graph naturally uses which structure, while breadth-first uses a queue?

Accepted Answer

A stack. Depth-first search follows one path as deep as possible, which a stack (or recursion) naturally supports.

Stack facts & stats

The basics