Prepare for Hack ReactorThe premiere coding bootcamp in California
Learn JavaScript in one week
An introductory course on JavaScript covering basic topics.
Basic array manipulation with functions in JavaScript
This question was taken from the Hack Reactor blog. This tutorial explains some common array functions and how to create and manipulate them.
Questions on closures
Closures are an important topic to understand when learning JavaScript. Here are a few common closure questions with solutions.
10 common JavaScript interview questions
Some common interview questions with topics such as decimal numbers, scope, private variables, and more.
Map, reduce, and filter - functional programming
Introduction to functional programming methods in JavaScript.
Counting steps using recursion
A lecturer at Hack Reactor wrote that recursion is an important topic to understand when applying to the bootcamp, so this tutorial provides a simple example.
Two sum problem
A popular interview question that requires you to determine if two numbers in an array sum to a specific value. A solution can be written that runs in linear time.
Subset sum problem
Important computer science question where the goal is to find a subset that sums to some number.
Stock maximum profit
Solution that explains how to calculate the maxiumum profit that could be made in a list of stock prices.
From Zero to Hack Reactor in 5 months
By Jennie Eldon: A detailed explanation on the path to learning to code and getting into Hack Reactor.
Hack Reactor Week 0: Getting Ready
By Andrew Zey: A blog post about the first few weeks at Hack Reactor and some prep work.
What I Studied Before Applying to Hack Reactor
By Amira Anuar: A blog post about prep work for Hack Reactor admissions.
First Factorial
For this challenge you will be determining the factorial for a given number.
87364 solutions
Solution
Longest Word
For this challenge you will be determining the largest word in a string.
69243 solutions
Solution
Letter Changes
For this challenge you will be manipulating characters in a string based off their positions in the alphabet.
66711 solutions
Solution
Simple Adding
For this challenge you will be adding up all the numbers from 1 to a certain argument.
54559 solutions
Solution
Letter Capitalize
For this challenge you will be capitalizing certain characters in a string.
46445 solutions
Solution
Simple Symbols
For this challenge you will be determining whether or not certain characters are in correct positions.
39513 solutions
Solution
Check Nums
For this challenge you will be comparing two numbers and determining which one is greater.
40020 solutions
Solution
Time Convert
For this challenge you will be determining the difference in hours and minutes between two given times.
30366 solutions
Solution
Alphabet Soup
For this challenge you will be sorting characters in a string.
28061 solutions
Solution
Vowel Count
For this challenge you will be counting all the vowels in a string.
15467 solutions
Solution
Word Count
For this challenge you will be determining how many words a sentence contains.
14612 solutions
Solution
Palindrome
For this challenge you will determine if a string is written the same way forward and backwards.
16645 solutions
Solution
Array Addition I
For this challenge you will determine if numbers in an array can add up to a certain number in the array.
8478 solutions
Solution
Letter Count I
For this challenge you will determine which word has the greatest number of repeated letters.
7777 solutions
Solution
Second GreatLow
For this challenge you will determine the second lowest and greatest numbers in an array.
12902 solutions
Solution
Division Stringified
For this challenge you will divide two numbers and return them in a certain format.
9686 solutions
Solution
Counting Minutes I
For this challenge you will return the total number of minutes between two times.
5731 solutions
Solution
Dash Insert
For this challenge you will be manipulating a string using dashes (-).
8527 solutions
Solution
Number Addition
For this challenge you will traverse a string searching for all the numbers and then you will add them up.
7941 solutions
Solution
Third Greatest
For this challenge you will determine the third largest string within an array.
7344 solutions
Solution
Powers of Two
For this challenge you will be determining whether or not a number is a power of two.
8228 solutions
Solution
Additive Persistence
For this challenge you will be determining the additive persistence for a given number.
5859 solutions
Solution
Multiplicative Persistence
For this challenge you will be determining the multiplicative persistence for a given number.
4517 solutions
Solution
Off Line Minimum
For this challenge you will be creating a subset of an array.
6070 solutions
Solution
Changing Sequence
For this challenge you will determine when an array changes sequences.
2494 solutions
Solution
Overlapping Ranges
For this practice test you will determine the intersection between two sets.
2491 solutions
Solution
Superincreasing
For this challenge you will determine if each number is greater than the sum of all previous elements in an array.
2535 solutions
Solution
Hamming Distance
For this challenge you will determine the difference between two strings.
1730 solutions
Solution
Rectangle Area
For this challenge you will determine the area of a rectangle.
2110 solutions
Solution
Bitwise One
For this challenge you will perform a bitwise operation on two binary numbers.
1716 solutions
Solution
Other Products
For this challenge you will return the product of a set of elements in an array.
1748 solutions
Solution
Wave Sorting
For this challenge you will determine if numbers in an array can be sorted in a particular way.
1215 solutions
Solution
Array Matching
For this challenge you will add elements from two arrays in a particular order.
1492 solutions
Solution
Longest Increasing Sequence
For this challenge you will compute the length of the longest increasing subsequence.
1179 solutions
Solution
Even Pairs
For this challenge you will determine if a pair of even numbers exists somewhere in a string.
1129 solutions
Solution
Next Palindrome
For this challenge you will be determining the next largest palindrome.
986 solutions
Solution
Largest Pair
For this challenge you will determine the largest double digit number.
1319 solutions
Solution
Nonrepeating Character
For this challenge you will find the first non-repeating character in a string.
974 solutions
Solution
Bitwise Two
For this challenge you will perform a bitwise operation on two binary numbers.
705 solutions
Solution
Power Set Count
For this challenge you will determine the length of a power set.
1034 solutions
Solution
Product Digits
For this challenge you will be determining the least amount of digits needed to produce a number.
1304 solutions
Solution
Palindrome Creator
For this challenge you will be determining if you can create a palindrome from a list of numbers.
1069 solutions
Solution
Basic Roman Numerals
For this challenge you will be converting a string of Roman numerals.
713 solutions
Solution
Food Distribution
For this challenge you will determine how to optimally distribute food to people.
614 solutions
Solution
Correct Path
For this challenge you will be traversing a matrix searching for the correct path to take.
1343 solutions
Solution
Scale Balancing
For this challenge you will be balancing a scale with weights on it.
1792 solutions
Solution
Three Numbers
For this challenge you will be searching for a set of numbers in a string.
683 solutions
Solution
Alphabet Searching
For this challenge you will determine if a set of characters exists in a string.
582 solutions
Solution
Time Difference
For this challenge you will be searching for the smallest time difference.
377 solutions
Solution
Triangle Row
For this challenge you will be adding up a whole row from Pascal's triangle.
367 solutions
Solution
Vowel Square
For this challenge you will determine if a square of vowels exists in a matrix.
1178 solutions
Solution
Closest Enemy II
For this challenge you will search in a matrix for an enemy.
1012 solutions
Solution
Number Stream
For this challenge you will determine if a stream of digits occurs in a string.
362 solutions
Solution
Largest Four
For this challenge you will need to find the four largest elements in an array.
539 solutions
Solution
Distinct Characters
For this challenge you will determine if a string contains some number of distinct characters.
386 solutions
Solution
Questions Marks
For this challenge you will be determining if a string follows a particular pattern.
2946 solutions
Solution
Camel Case
For this challenge you will be converting a string into camel case format.
454 solutions
Solution
ASCII Conversion
For this challenge you will be replacing certain characters in a string.
311 solutions
Solution
Simple Evens
For this challenge you will be checking whether a number is even.
427 solutions
Solution
Snake Case
For this challenge you will be converting a string into snake case format.
373 solutions
Solution
Sum Multiplier
For this challenge you will determine if two numbers can be multiplied to some specific number.
469 solutions
Solution
String Merge
For this challenge you will be merging two different strings together.
440 solutions
Solution
One Decremented
For this challenge you will be counting how many times a specific pattern occurs in a large number.
414 solutions
Solution
Element Merger
For this challenge you will be combining all of the elements in an array into a single number.
444 solutions
Solution
Serial Number
For this challenge you will be determining if a string produces a valid serial number.
567 solutions
Solution
String Periods
For this challenge you will need to find the smallest repeating substring.
488 solutions
Solution
Palindrome Swapper
For this challenge you will determine if a palindrome can be created in a string.
288 solutions
Solution
Remove Brackets
For this challenge you will determine how to create evenly matched brackets.
414 solutions
Solution
Command Line
For this challenge you will be parsing a command line string and counting its characters.
185 solutions
Solution
Star Rating
For this challenge you will be calculating how to display a 5 star rating.
383 solutions
Solution
Moving Median
For this challenge you will calculate the median in an array within a sliding window.
157 solutions
Solution
Group Totals
For this challenge you will be adding values from key, value pairs.
109 solutions
Solution