R

E

A

C

T

O

xamples 

epeat

ode

pproach

ptimize

est

{ Bracket
Balancing }

The Question

One of your colleagues insists on writing all code in Notepad, resulting in code that won't run because the brackets, braces, and parenthesis are not properly balanced. You decide to write a bracket validator to check whether the brackets /braces/ parenthesis are valid.

Notes

• You have already written a RegEx to get rid of the non-brackets from the input string (i.e. your input will be all brackets, parenthesis, and braces)
• For the purpose of the problem these are considered 'brackets': 

​[ ] ( ) { }

Question

Given an input string return a boolean stating whether or not the brackets are balanced.

What are the expected outputs for each of these?

"{ [ ] ( ) }"

"{ [ ( ] ) }"

"{ [ }"

"{ [ text ( [  is { ( )[ totes]{ f } i } n ] e ) ] }"

One approach

• Each closing bracket should correspond to the nearest opening bracket that it pairs with
• Every opening and closing bracket should be in a pair
• You can keep track of these in a First In Last Out data structure

Possible Solution

Conclusion  

https://repl.it/K3WP/2

• Data structure principles can come in handy even when you are not explicitly creating a certain structure
• You can use arrays and array methods in Javascript to create an array that basically behaves like a stack/queue

Interview Tips

• There are many ways to solve this!
• Feel free to give them the RegEx, if they begin by saying, I know I could use RegEx but don't know exactly that it would look like..