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Required fields*

Rev

Required fields*

Pointlessly make your way down the alphabet

Disclaimer: This challenge inspired by me spending the morning debugging recursive functions, which have been frying my brain a little.

Here's an example of recursion, from a letter, we keep going to the previous letter of the alphabet, printing out each one as we go, until we hit the letter a, then we print that and stop. We do this for each letter in a string and there's a pretty pattern at the end of it.

The task

Start with a string of characters
- The input string may only contain the lower-case letters a-z and the space character.
For each letter, produce a line of text (terminal output or variable or whatever)
- Print out the letter
- Print out the previous letter (on the same line)
- Print out the previous letter (on the same line)
- Print out the previous letter (on the same line)
- ...
- If the letter is 'a', print it out and move to the next line.
- If it's a space, print out an empty line (or one just containing the space character.

The rules

It's golf, try and make your code short.
Any language you like.
Please include a link to an online interpreter.
The output should be human-readable (e.g. I can't work it out from a list of bytes.
Follow the rules of the standard loopholes ̄\_(ツ)_/ ̄
Recursion is not mandated by the rules, but it's probably necessary.

Test Cases

Input: 'abcdefghijklmnopqrstuvwxyz' Output:

a
ba
cba
dcba
edcba
fedcba
gfedcba
hgfedcba
ihgfedcba
jihgfedcba
kjihgfedcba
lkjihgfedcba
mlkjihgfedcba
nmlkjihgfedcba
onmlkjihgfedcba
ponmlkjihgfedcba
qponmlkjihgfedcba
rqponmlkjihgfedcba
srqponmlkjihgfedcba
tsrqponmlkjihgfedcba
utsrqponmlkjihgfedcba
vutsrqponmlkjihgfedcba
wvutsrqponmlkjihgfedcba
xwvutsrqponmlkjihgfedcba
yxwvutsrqponmlkjihgfedcba
zyxwvutsrqponmlkjihgfedcba

Input: 'zyxwvutsrqponmlkjihgfedcba'

zyxwvutsrqponmlkjihgfedcba
yxwvutsrqponmlkjihgfedcba
xwvutsrqponmlkjihgfedcba
wvutsrqponmlkjihgfedcba
vutsrqponmlkjihgfedcba
utsrqponmlkjihgfedcba
tsrqponmlkjihgfedcba
srqponmlkjihgfedcba
rqponmlkjihgfedcba
qponmlkjihgfedcba
ponmlkjihgfedcba
onmlkjihgfedcba
nmlkjihgfedcba
mlkjihgfedcba
lkjihgfedcba
kjihgfedcba
jihgfedcba
ihgfedcba
hgfedcba
gfedcba
fedcba
edcba
dcba
cba
ba
a

Input: 'hello world' Output:

hgfedcba
edcba
lkjihgfedcba
lkjihgfedcba
onmlkjihgfedcba
wvutsrqponmlkjihgfedcba
onmlkjihgfedcba
rqponmlkjihgfedcba
lkjihgfedcba
dcba

Answer*

# [R], <s>63</s> <s>62</s> 61 bytes
-16 bytes thanks to Giuseppe

-7 more bytes, again, thanks to Giuseppe

-1 byte adding a line break in place of `\n`

-1 byte thanks to Robin Ryder



 for(l in utf8ToInt(scan(,""))-96)cat(letters[l:0],'
 ',sep="")

[Try it online!][TIO-k3abrdkt]

[R]: https://www.r-project.org/
[TIO-k3abrdkt]: https://tio.run/##DcoxCsMwDADAva8QXmKDA5lCW8gDumcLHYSjOAZFKrb6frc3X@390OoZisDXjvuqLzHfEoqPzoUwPuaQ0DyTGdW28XN6x@E2xEaf5R@6O6kSFMALku5FMiBk1R3SicwkmVz/AQ "R – Try It Online"

# [R], 86 bytes (my original answer)



 x=utf8ToInt(scan(,''));s=sapply;cat(gsub(" .+"," ",s(s(x,`:`,97),intToUtf8)),sep="\n")

Ungolfed:

 x=utf8ToInt(scan(,'')) #Takes input, converts to ASCII
 s=sapply; #Alias sapply function to save a byte
 s(x,`:`,97) #Create vector from 97 to respective ASCII value
 s( ,intToUtf8) #Convert to character
 gsub(" .+"," ", ) #Removes everything after space
 cat( ,sep="\n") #Outputs to console


[Try it online!][TIO-k38vnox0]

Could likely be golfed.

NOTE: It does not use recursion. I do not know whether that would be shorter or not. I'll experiment later.


[R]: https://www.r-project.org/
[TIO-k38vnox0]: https://tio.run/##Dcw7DsMgDADQq1heYqtW136iHKB7snUIJZQgUUAxkdLT074DvK21Y9jr@zrmR6qk1iSSrmPudVBTSvz21lTyur8I4XxCQUBRUjpkvs9yu7CEVMc8/Q9mUVcGfCbkhqvbHAQwH7B5CcmDAZ/zAnY1MbrkHbYf "R – Try It Online"

If this is an answer to a challenge…

…Be sure to follow the challenge specification. However, please refrain from exploiting obvious loopholes. Answers abusing any of the standard loopholes are considered invalid. If you think a specification is unclear or underspecified, comment on the question instead.
…Try to optimize your score. For instance, answers to code-golf challenges should attempt to be as short as possible. You can always include a readable version of the code in addition to the competitive one. Explanations of your answer make it more interesting to read and are very much encouraged.
…Include a short header which indicates the language(s) of your code and its score, as defined by the challenge.

More generally…

…Please make sure to answer the question and provide sufficient detail.
…Avoid asking for help, clarification or responding to other answers (use comments instead).

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1

\$\begingroup\$ 80 bytes \$\endgroup\$

Giuseppe
– Giuseppe

2019年11月21日 19:37:28 +00:00
Commented Nov 21, 2019 at 19:37
\$\begingroup\$ Just when I felt confident I had found a solid answer, @Giuseppe comes back again with something better! As expected... \$\endgroup\$

Sumner18
– Sumner18

2019年11月21日 19:52:02 +00:00
Commented Nov 21, 2019 at 19:52
2

\$\begingroup\$ ooh, or 63 bytes -- I'm just very excited to get back into golfing!!!! \$\endgroup\$

Giuseppe
– Giuseppe

2019年11月21日 20:36:51 +00:00
Commented Nov 21, 2019 at 20:36
1

\$\begingroup\$ Aha, I found 1 more byte! I don't feel as useless anymore. Haha \$\endgroup\$

Sumner18
– Sumner18

2019年11月21日 20:44:53 +00:00
Commented Nov 21, 2019 at 20:44
1

\$\begingroup\$ 61 bytes \$\endgroup\$

Robin Ryder
– Robin Ryder

2019年11月22日 13:08:58 +00:00
Commented Nov 22, 2019 at 13:08

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