Hi smile Here s a programming puzzle I solved with Kotlin Pl

Question

Hi smile Here s a programming puzzle I solved with Kotlin Please pick it apart if ya like I ve been doing Kotlin for like 5 days But also lemme know if the approach was off or unclear tldr problem description print a diamond start from A to `someLetter` ``` A B B C C B B A ``` The problem description amp the solution <https gist github com adnauseum 4a7c9762d57f3b82b1dd18b1204af3cb> If you want to review it 1 thanks 2 leave a comment in a thread or on the gist whatever is easiest for you bow THANK YOU Actually the fact that anybody would leave a comment is mind blowing so thanks for even reading and putting in the effort

Timmy · Answer

Looks good I did the challenge before looking at your code and came up with the same algorithm and mostly the same code Here is what I did differently Since no OOP is involved a top level function is enough no need for the DiamondPrinter class My return type is the complete string non nullable Your list is fine but should be non nullable I used mapIndexed which does the same as withIndex map I used dropLast 1 instead of slice since it has a more readable meaning In the when statement multiple conditions have the same effect so combine them like so `leftOfMiddleIndex rightOfMiddleIndex gt letter` Skipped some variable definitions leftOfMiddleIndex and rightOfMiddleIndex and just inlined them to where they are used not that important I used an imperative approach to constructing the lines with stringBuilder `repeat numLettersPerRow append ` Might be more performant than constructing a list then joining it but at this scale it doesn t matter Actually I like your approach better Used a + instead of plus I didn t use a separate function makeRow and just had that in the lambda If you want to keep your makeRow function use a method reference `lettersUsedInDiamond mapIndexed makeRow `

skendrick · Answer

Ahh this is perfect The class and return type were part of the website s requirement I found the problem on <http exercism io|exercism io> hate the name of that site smile These are great insights THANK YOU smile

skendrick · Answer

Wow < Timmy> just implemented your suggestions These were exactly the things I was looking for Tytyty bow

skendrick · Answer

Now how can I get this whole thing to be one line of code thinking face laughing

bjonnh · Answer

fun diamond size Int List lt String gt require size in 1 26 return 0 until size map var str = repeat size it 1 str += str += it+65 toChar repeat 2 it 1 str += if it =0 str += it+65 toChar repeat size it 1 str+= str += n str let it + it dropLast 1 reversed

bjonnh · Answer

is one way

bjonnh · Answer

fun diamond size Int List lt String gt require size in 1 26 return 0 until size map var str = repeat size it 1 str += str += it+65 toChar repeat 2 it 1 str += str mapIndexed index it gt it+it dropLast max 2 index 1 1 reversed + n let it + it dropLast 1 reversed

bjonnh · Answer

that s another way that use symmetry

bjonnh · Answer

And this is an even more functional way

bjonnh · Answer

fun diamond size Int List lt String gt require size in 1 26 return 0 until size map i gt i + 65 toChar let c gt Array size 2 1 also it size i 1 = c it size + i 1 = c joinToString + n let it + it dropLast 1 reversed