Sololearn Coding Challenges

There are all 72 problems from SoloLearn Code Coach with full descriptions and my solutions in Java. The problems grouped by dificulty: Easy, Medium, Hard. The codes have written on mobile device in Sololearn sandbox, sucessfully run and passes all tests by Sololearn. The link to my profile at Sololearn: https://www.sololearn.com/Profile/15186890/

As an answer to the #OneLiners challenge from SoloLearn I also created One-Line solutions in Ruby and One-Statement solutions in Java language for about 60% problems.

Easy

Description	Java	Used Java API classes and methods, notes
Popsicles	Popsicles.java	Ternary operator
Halloween Candy	HalloweenCandy.java	Math
Fruit Bowl	FruitBowl.java
Ballpark Orders	BallparkOrders.java	Map, BigDecimal, Stream, Scaner::tokens (Java 11)
Cheer Creator	CheerCreator.java	String::repeat (Java 11)
Skee-ball	SkeeBall.java
Paint Costs	PaintCosts.java	BigDecimal, RoundingMode
Argentina	Argentina.java	I use multiplication to keep max precision
Balconies	Balconies.java	Scanner::useDelimiter
Candles	Candles.java
Duct Tape	DuctTape.java	Math
Easter Eggs	EasterEggs.java	Ternary operator
Guard Flamingos	GuardFlamingos.java
Gotham City	GothamCity.java	MessageFormat::format
Hovercraft	Hovercraft	BigDecimal
Izzy the Iguana	IzzyIguana.java	Map, Scaner::tokens (Java 11)
Kaleidoscopes	Kaleidoscopes.java	BigDecimal (There is errors in SoloLearn tests)
Jungle Camping	JungleCamping.java	Map, Scaner::tokens (Java 11)
Land Ho!	LandHo.java
Neverland	Neverland.java	System.out::printf
Extra-Terrestrials	ExtraTerrestrials.java	StringBuilder::reverse
Zip Code Validator	ZipCodeValidator.java	Pattern::matches
Vowel Counter	VowelCounterRE.java	String::replaceAll
Isogram Detector	IsogramDetector.java	Pattern::matches
Multiples	Multiples.java	IntStream, lambda
Number of Ones	NumberOfOnes.java	Integer::bitCount

Medium

Description	Java	Used Java API classes and methods, notes
Pig Latin	PigLatinRE.java	String::replaceAll, RegEx
_	PigLatinStream.java	Scanner::tokens, lambda
_	PigLatinClassic.java	System.out::printf
Safety Deposit Boxes	SafetyDepositBoxes.java	String::replaceAll, RegEx (tricky?)
Roadrunner	Roadrunner.java
Snap, Crackle and Pop	SnapCrackleAndPop.java	Stream, lambda
Deja Vu	DejaVu.java	Pattern::matches
The Spy Life	TheSpyLife.java	StringBuilder
Hex Color Code Generator	HexColorCodeGenerator.java	System.out::printf
Symbols	Symbols.java	String::replaceAll, RegEx
Super Sale	SuperSale.java	Stream
Duty Free	DutyFree.java	Stream
Carrot Cake	CarrotCake.java	System.out::printf
Building Blocks	BuildingBlocks.java	IntStream::generate
Name Buddy	NameBuddy.java	String::concat
_	NameBuddyRegEx.java	String::matches
That's odd...	ThatsOdd.java	IntStream
No Numerals	NoNumerals.java	Map, Stream, lambda
Secret Message	SecretMessage.java	Stream, lambda
Divisible	Divisible.java	Stream, lambda
Even Numbers	EvenNumbers.java	IntStream
Military Time	MilitaryTime.java	Date & Time API Java 11
Tax Free	TaxFree.java	Stream
How Far?	HowFar.java	String::replaceAll, RegEx
Average Word Length	AverageWordLength.java	String::split, String::replaceAll
.	AverageWordLengthStream.java	Stream, Collectors::averagingInt
YouTube Link Finder	YouTubeLinkFinder.java	String::replaceAll, RegEx
Convert US date to EU date	ConvertDate.java	Date & Time API Java 11
Day of the Week	DayOfWeek.java	Date & Time API Java 11
Camel to Snake	CamelToSnake.java	String::replaceAll, RegEx
Days between dates	DaysBetweenDates.java	Date & Time API Java 11
Text Decompressor	TextDecompressor.java	Stream
Snowballing Numbers	SnowballingNumbers.java	Stream
Flowing Words	FlowingWords.java	RegEx
Splitting Strings	SplittingStrings.java	String::format, String::split, String::join, RegEx
Missing Numbers	MissingNumbers.java	Stream
Initials	Initials.java	Stream, RegEx
Credit Card Validator	CreditCardValidator.java	StringBuilder, Stream
CMYK to RGB	CmykToRgb.java	Math, float

Hard

Description	Java	Used Java API classes and methods, notes
New Driver's License	NewDriversLicense.java	Stream, lambda
It's a Sign	ItsSign.java	StringBuilder, Stream
Mathematics	Mathematics.java	Interface, Lambda, RegEx, Collections, Recursion
Password Validation	PasswordValidation.java	RegEx
Security	Security.java	RegEx
2D Map	Map2D.java	Math, String::indexOf
Hofstadter's Q-Sequence	HofstadtersQSequence.java
Digits of Pi	PiCalculation.java	BigDecimal, Algorithm
Longest Common Substring	Longest Common Substring
Poker Hand	PokerHand.java	Stream, RegEx
Word Rank	Word Rank