Data Structures

Question 1

What does the acronym LIFO mean?

Answer 1

Last In First Out

Can refer to data structures that limit interaction to a single end. The last value pushed into the data structure is the first value popped out of it.

Question 2

What methods are available on a Stack data structure?

Answer 2

.push(value) - adds a value to the top of the stack
.pop( ) - returns the top value in the stack and removes it
.peek( ) - returns the top value in the stack without removing

Question 3

What must you do the access the value at an arbitrary point in a stack (not just the “top”)?

Answer 3

If the stack can be mutated: call pop( ) on the stack the necessary amount of times

No mutation: call pop( ) on the stack and store all the values in an array. Get the desired value then push the values from the array back onto the stack in reverse order

Question 4

What does the acronym FIFO mean?

Answer 4

First In First Out

The first thing enqueued into a stack is the first thing out. Head of the structure is processed first

Question 5

What methods are available on a Queue data structure?

Answer 5

.enqueue(value) - adds a value to the end of the queue

.dequeue( ) - removes and returns the value at the start of the queue

Question 6

What must you do to access the value at an arbitrary point in a queue (not just the “front”)?

Answer 6

Must cycle through the queue the amount of times necessary while dequeueing and enqueueing the first item

Question 7

How are linked lists different from an array?

Answer 7

Can’t access arbitrary nodes.

Can only traverse them in one direction

Question 8

How would you access an arbitrary node in a linked list (not just the “head”)?

Answer 8

Have to go down the list of nodes the number of times desired and get the data from that node