# Golff y Côd - Treiglad

## Challenge

Given a word in Welsh, output all of the possible mutated forms of the word.

## Mutations

A mutation is a change of the first letter of a word when following certain words or in certain grammatical contexts.

In Welsh, the following are considered "consonants":

b c ch d dd f ff g ng h l ll m n p ph r rh s t th


Note that multiple character consonants such as ch, ng and rh are counted as one letter in Welsh, and therefore one consonant.

The other letters in the Welsh alphabet are vowels, listed below:

a e i o u w y


See below, all of the mutations with the original letter on the left and the resulting mutated letters on the right:

Original | Mutations
---------+---------------
p        | b mh ph
t        | d nh th
c        | g ngh ch
b        | f m
d        | dd n
g        | [no letter] ng
m        | f
ll       | l
rh       | r


Here, [no letter] means that the g is removed from the start of the word.

Note that there are some consonants which do not mutate:

ch
dd
f
ff
j
l
n
ng
ph
r
s
th


Vowels may also be found at the start of words but do not mutate:

a
e
i
o
u
w
y


## Examples

Input: dydd

Output:

dydd
ddydd
nydd


Input: pobl

Output:

pobl
bobl
mhobl
phobl


Input: gwernymynydd

Output:

gwernymynydd
wernymynydd
ngwernymynydd


Input: ffrindiau

Output:

ffrindiau


Input: enw

Output:

enw


Input: theatr

Output:

theatr


On the request of ArtOfCode ;)

Input: llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch

Output:

llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch
lanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch


## Rules

The input will only ever be one word.

There will always be more letters after the leading consonant in your input.

## Winning

The shortest code in bytes wins.

• New test case: llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch – ArtOfCode Sep 10 '16 at 8:01
• Another test case theatr; t mutates but th doesn't. – Antti Haapala Sep 10 '16 at 9:32
• Should be 'Golff y Côd' - 'yr' only comes before a vowel, you use 'y' before a consonant. – Gareth Sep 10 '16 at 12:25
• If anyone's interested in the complicated rules regarding mutation in Welsh, there's an app called 'Ap Treiglo' which gives the rules and lists many of the words which cause mutations in the following word. – Gareth Sep 10 '16 at 12:38
• @Beta Decay Yeah, for the last 5 years. Rhyl before that, for my sins. – Gareth Sep 10 '16 at 20:02

# JavaScript (ES6), 180 bytes

x=>x.replace(/^([cpt](?!h)|d(?!d)|[bgm]|ll|rh)(.+)/,(_,y,z)=>({p:"b mh ph",t:"d nh th",c:"g ngh ch",b:"f m",d:"dd n",g:" ng",m:"f"}[y]||y[0]).split .map(b=>a.push(b+z)),a=[x])&&a


Outputs as an array of strings. This is my first try, so it's almost certainly not optimal.

### Try it out

f=x=>x.replace(/^([cpt](?!h)|d(?!d)|[bgm]|ll|rh)(.+)/,(_,y,z)=>({p:"b mh ph",t:"d nh th",c:"g ngh ch",b:"f m",d:"dd n",g:" ng",m:"f"}[y]||y[0]).split .map(b=>a.push(b+z)),a=[x])&&a
<input id=A value="pobl"><button onclick="B.innerHTML=f(A.value).join('<br>')">Run</button><br>
<pre id=B>

• It's not optimal, but my PC decided to switch itself off, and I no longer remember what optimisation I was able to make. – Neil Sep 11 '16 at 0:29

## C#, 356 338360 bytes

I know that C# is a poor choice for code golf, but it's worth the shot:

Third attempt, all cases now pass, including th- ph- etc. This adjustment cost roughly 18 bytes.

Thanks pinkfloydx33 for the tips saving 24 bytes!

namespace System{using Linq;using S=String;class P{static void Main(S[]a){Action<S>w=Console.WriteLine;w(a[0]);foreach(S r in"th-dd-ch-ph-p.b.mh.ph-t.d.nh.th-c.g.ngh.ch-b.f.m-d.dd.n-g..ng-m.f-ll.l-rh.r".Split('-')){var b=r.Split('.');if(a[0].StartsWith(b[0])){foreach(S f in b.Skip(1))w(Text.RegularExpressions.Regex.Replace(a[0],$"^{b[0]}",f));break;}}}}}  ## Output $> ./p gwernymynydd
gwernymynydd
wernymynydd
ngwernymynydd


## Formatted Version

    namespace System {
using Linq;
using S = String;

class P {
static void Main(S[] a) {
Action<S> w = Console.WriteLine;
w(a[0]);
foreach (S r in "th-dd-ch-ph-p.b.mh.ph-t.d.nh.th-c.g.ngh.ch-b.f.m-d.dd.n-g..ng-m.f-ll.l-rh.r"
.Split('-')) {
var b = r.Split('.');
if (a[0].StartsWith(b[0])) {
foreach (S f in b.Skip(1))
w(Text.RegularExpressions.Regex.Replace(a[0], $"^{b[0]}", f)); break; } } } } }  • $"{f}" should just be f, you can also save the first call to write line, as well as the action, by not skipping the first element in b (saving the skip as well) and just replacing the first item with itself (I think). You also only make one call to regex so Caching/renaming the import costs more than just Text.RegularExpressions.Regex.Replace(...) in the body. The break is also superfluous since it's only gonna match once doesnt matter if it loops through to the end – pinkfloydx33 Sep 10 '16 at 3:08
• There are no poor choices of language for golf - you are competing against anyone else who wants to try and beat you in the same language. Plus C# was once the golfing language of choice for Jon Skeet... – trichoplax Sep 10 '16 at 8:32
• @pinkfloydx33 Thanks for the tips! However I can't remove the first Console.WriteLine call because this will skip outputting the word in case there are no replacements for it. I am sure there is a way how to optimize it by changing the condition. – grizzly Sep 10 '16 at 17:06
• I just spotted theatr case and it seems it isn't mutating correctly. – grizzly Sep 10 '16 at 17:07
• Yeah there are several test cases that don't pass at the moment because PH, TH, CH and DD do not get transformed – pinkfloydx33 Sep 10 '16 at 17:59

## Python 3, 196,189 185 bytes

Original attempt

w=input();print(w);[w.startswith(a)and[print(w.replace(a,i,1))for i in
r]+exit()for(a,*r)in(j.split(',')for j
in'th rh ph p,b,mh,ph t,d,nh,th c,g,ngh,ch b,f,m d,dd,n g,,ng m,f ll,l rh,r'.split())]


Vaultah noted that not w.find(a) would be a replacement for w.startswith(a) that would save 2 characters. But instead of not x and y we can use x or y which saves some characters more:

w=input();print(w);[w.find(a)or[print(w.replace(a,i,1))for i in
r]+exit()for(a,*r)in(j.split(',')for j
in'th rh ph p,b,mh,ph t,d,nh,th c,g,ngh,ch b,f,m d,dd,n g,,ng m,f ll,l rh,r'.split())]


Yet further savings by replacing w.replace(a,i,1) with i+w[len(a):]:

w=input();print(w);[w.find(a)or[print(i+w[len(a):])for i in
r]+exit()for(a,*r)in(j.split(',')for j
in'th rh ph p,b,mh,ph t,d,nh,th c,g,ngh,ch b,f,m d,dd,n g,,ng m,f ll,l rh,r'.split())]


Then I noticed that there was a bug, rh was listed twice; once in my short-circuit list that would take care of those double-letter consonants. Unfortunately dd was missing from there, so no savings, and we have

w=input();print(w);[w.find(a)or[print(i+w[len(a):])for i in
r]+exit()for(a,*r)in(j.split(',')for j
in'th ph dd p,b,mh,ph t,d,nh,th c,g,ngh,ch b,f,m d,dd,n g,,ng m,f ll,l rh,r'.split())]


Given any of the sample inputs, it gives the desired output; given

gorsaf


it outputs

gorsaf
orsaf
ngorsaf


and given input

theatr


it prints

theatr


## PowerShell v3+, 254 231 bytes

param($a)$a;$z=-join$a[1..$a.length] if(($x=@{112='b mh ph';116='d nh th';99='g ngh ch';98='f m';100='dd n';109='f'})[+$a[0]]-and$a-notmatch'^[cpt]h|^dd'){-split$x[+$a[0]]|%{"$_$z"}}
($z,"ng$z")*($a[0]-eq103)$z*($a-match'^ll|^rh')  working to golf further... ### Examples (Output is space-separated because that's the default Output Field Separator for stringified arrays. I don't know if the words I used for testing are actual words, but they fit the exceptions.) PS C:\Tools\Scripts\golfing> 'dydd','pobl','gwernymynydd','ffrindiau','enw','rhee','llewyn','chern','ddydd','phobl'|%{"$_ --> "+(.\golff-yr-cod.ps1 $_)} dydd --> dydd ddydd nydd pobl --> pobl bobl mhobl phobl gwernymynydd --> gwernymynydd wernymynydd ngwernymynydd ffrindiau --> ffrindiau enw --> enw rhee --> rhee hee llewyn --> llewyn lewyn chern --> chern ddydd --> ddydd phobl --> phobl  ## C#, 349 bytes Based on @grizzly's submission, but corrected to work with the consonants that don't get transformed (ph/ch/th/dd) that it wasn't working with, plus trimmed some excess out. Hope that's alright? I had it down to 290 until I realized that I was missing the th/ch/ph/dd cases :-(. Adding in the Regex call killed it namespace System{class P{static void Main(string[]a){var x=a[0];if(!Text.RegularExpressions.Regex.IsMatch(x,"^[pct]h|^dd"))foreach(var r in"p.b.mh.ph-t.d.nh.th-c.g.ngh.ch-b.f.m-d.dd.n-g..ng-m.f-ll.l-rh.r".Split('-')){var b=r.Split('.');if(a[0].StartsWith(b[0]))for(int i=1;i<b.Length;)x+='\n'+b[i++]+a[0].Substring(b[0].Length);}Console.Write(x);}}}  Interesting note, never knew that you could omit the space between var r in"string" Formatted: namespace System { class P { static void Main(string[] a) { var x = a[0]; if (!Text.RegularExpressions.Regex.IsMatch(x, "^[pct]h|^dd")) foreach (var r in"p.b.mh.ph-t.d.nh.th-c.g.ngh.ch-b.f.m-d.dd.n-g..ng-m.f-ll.l-rh.r".Split('-')) { var b = r.Split('.'); if (a[0].StartsWith(b[0])) for (int i = 1; i < b.Length;) x += '\n' + b[i++] + a[0].Substring(b[0].Length); } Console.Write(x); } } }  # Perl 6, 162 bytes {/^(.|<[cprt]>h|dd|ff|ng|ll)(.*)/;(%('p',<b mh ph>,'t',<d nh th>,'c',<g ngh ch>,'b',<f m>,'d',<dd n>,'g',«'' ng»,'m',<f>,'ll',<l>,'rh',<r>){$0}//~$0).map(*~$1)}


Try it online!