Indexable quine

Question

The goal of this challenge is to make a program that outputs the nth letter of its source code where n is given as input to the program. Like most quine challenges, you are not allowed to read your source code as a file or use any builtin quine functions.

Input

An integer 0 <= n < len(program).

Output

The nth character (not byte) of your program.

Winning

Like most codegolf questions, you win the challenge by using the lowest number of bytes to solve the challenge.

Bonuses

-5% If your program supports negative indices python style (e.g. -1 would be the last character of your program). If used with the below bonus, your ranges must support negative indices.
-20% If your program supports ranges as input (any format) in addition to the above requirements.
-25% If your program complete both bonuses.

Leaderboards

Here is a Stack Snippet to generate both a regular leaderboard and an overview of winners by language.

To make sure that your answer shows up, please start your answer with a headline, using the following Markdown template:

# Language Name, N bytes

where N is the size of your submission. If you improve your score, you can keep old scores in the headline, by striking them through. For instance:

# Ruby, <s>104</s> <s>101</s> 96 bytes

If there you want to include multiple numbers in your header (e.g. because your score is the sum of two files or you want to list interpreter flag penalties separately), make sure that the actual score is the last number in the header:

# Perl, 43 + 2 (-p flag) = 45 bytes

You can also make the language name a link which will then show up in the leaderboard snippet:

# [><>](http://esolangs.org/wiki/Fish), 121 bytes

var QUESTION_ID=70727,OVERRIDE_USER=32700;function answersUrl(e){return"https://api.stackexchange.com/2.2/questions/"+QUESTION_ID+"/answers?page="+e+"&pagesize=100&order=desc&sort=creation&site=codegolf&filter="+ANSWER_FILTER}function commentUrl(e,s){return"https://api.stackexchange.com/2.2/answers/"+s.join(";")+"/comments?page="+e+"&pagesize=100&order=desc&sort=creation&site=codegolf&filter="+COMMENT_FILTER}function getAnswers(){jQuery.ajax({url:answersUrl(answer_page++),method:"get",dataType:"jsonp",crossDomain:!0,success:function(e){answers.push.apply(answers,e.items),answers_hash=[],answer_ids=[],e.items.forEach(function(e){e.comments=[];var s=+e.share_link.match(/\d+/);answer_ids.push(s),answers_hash[s]=e}),e.has_more||(more_answers=!1),comment_page=1,getComments()}})}function getComments(){jQuery.ajax({url:commentUrl(comment_page++,answer_ids),method:"get",dataType:"jsonp",crossDomain:!0,success:function(e){e.items.forEach(function(e){e.owner.user_id===OVERRIDE_USER&&answers_hash[e.post_id].comments.push(e)}),e.has_more?getComments():more_answers?getAnswers():process()}})}function getAuthorName(e){return e.owner.display_name}function process(){var e=[];answers.forEach(function(s){var r=s.body;s.comments.forEach(function(e){OVERRIDE_REG.test(e.body)&&(r="<h1>"+e.body.replace(OVERRIDE_REG,"")+"</h1>")});var a=r.match(SCORE_REG);a&&e.push({user:getAuthorName(s),size:+a[2],language:a[1],link:s.share_link})}),e.sort(function(e,s){var r=e.size,a=s.size;return r-a});var s={},r=1,a=null,n=1;e.forEach(function(e){e.size!=a&&(n=r),a=e.size,++r;var t=jQuery("#answer-template").html();t=t.replace("{{PLACE}}",n+".").replace("{{NAME}}",e.user).replace("{{LANGUAGE}}",e.language).replace("{{SIZE}}",e.size).replace("{{LINK}}",e.link),t=jQuery(t),jQuery("#answers").append(t);var o=e.language;/<a/.test(o)&&(o=jQuery(o).text()),s[o]=s[o]||{lang:e.language,user:e.user,size:e.size,link:e.link}});var t=[];for(var o in s)s.hasOwnProperty(o)&&t.push(s[o]);t.sort(function(e,s){return e.lang>s.lang?1:e.lang<s.lang?-1:0});for(var c=0;c<t.length;++c){var i=jQuery("#language-template").html(),o=t[c];i=i.replace("{{LANGUAGE}}",o.lang).replace("{{NAME}}",o.user).replace("{{SIZE}}",o.size).replace("{{LINK}}",o.link),i=jQuery(i),jQuery("#languages").append(i)}}var ANSWER_FILTER="!t)IWYnsLAZle2tQ3KqrVveCRJfxcRLe",COMMENT_FILTER="!)Q2B_A2kjfAiU78X(md6BoYk",answers=[],answers_hash,answer_ids,answer_page=1,more_answers=!0,comment_page;getAnswers();var SCORE_REG=/<h\d>\s*([^\n,]*[^\s,]),.*?([\d\.]+)(?=[^\n\d<>]*(?:<(?:s>[^\n<>]*<\/s>|[^\n<>]+>)[^\n\d<>]*)*<\/h\d>)/,OVERRIDE_REG=/^Override\s*header:\s*/i;

body{text-align:left!important}#answer-list,#language-list{padding:10px;width:290px;float:left}table thead{font-weight:700}table td{padding:5px}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <link rel="stylesheet" type="text/css" href="//cdn.sstatic.net/codegolf/all.css?v=83c949450c8b"> <div id="answer-list"> <h2>Leaderboard</h2> <table class="answer-list"> <thead> <tr><td></td><td>Author</td><td>Language</td><td>Size</td></tr></thead> <tbody id="answers"> </tbody> </table> </div><div id="language-list"> <h2>Winners by Language</h2> <table class="language-list"> <thead> <tr><td>Language</td><td>User</td><td>Score</td></tr></thead> <tbody id="languages"> </tbody> </table> </div><table style="display: none"> <tbody id="answer-template"> <tr><td>{{PLACE}}</td><td>{{NAME}}</td><td>{{LANGUAGE}}</td><td>{{SIZE}}</td><td><a href="{{LINK}}">Link</a></td></tr></tbody> </table> <table style="display: none"> <tbody id="language-template"> <tr><td>{{LANGUAGE}}</td><td>{{NAME}}</td><td>{{SIZE}}</td><td><a href="{{LINK}}">Link</a></td></tr></tbody> </table>

Answer 1

Pyth, 0.75

(Also happens to be a CJam polyglot, and probably many other languages.)

0

Expects input on STDIN:

llama@llama:~$ echo 0..0 | pyth -c '0'
0

Any single digit works, of course. Not exactly the most interesting challenge in Pyth.

Answer 2

Javascript ES6, 31 bytes

$=_=>`$=${$};$()`[prompt()];$()

Explanation

The standard quine framework:

$=_=>`$=${$};$()`;$()

[prompt()], which is the addon, gets the value at the input index of the resulting quine string.

Answer 3

, 9 chars / 19 bytes

⟮ɕṡ+ᶈ0)⎖ï

Try it here (Firefox only).

Ay, 19th byte!

0 works too (and is much better), but it's way too trivial for my liking.

In addition, ℹ ï,⧺ï would also work, but quine functions aren't allowed.

Explanation

The standard quine framework is ⟮ɕṡ+ᶈ0.

)⎖ï takes the resulting quine string and gets the character at the input index.

---

Bonus solution, 11.4 chars / 25.65 bytes

⟮ᵖ…ɕṡ+ᶈ0;ôᵍï

Try it here (Firefox only).

This one qualifies for the 5% bonus, but still does not beat my original submission.

Explanation

This one uses the stack. ᵖ…ɕṡ+ᶈ0; just pushes the quine string's individual characters to the stack, and ôᵍï directly outputs the character at the input index (positive or negative) in the stack.

Answer 4

CJam, 12.35 bytes

{s"_~"+ri=}_~

The program is 13 bytes long and qualifies for the × 0.95 bonus. Try it online!

How it works

{         }      Define a code block.
           _~    Push a copy and execute the copy.
 s               Cast the original code block to string.
  "_~"+          Append "_~".
       ri        Read an integer from STDIN.
         =       Retrieve the character at that index.

Answer 5

Ruby, 53 * 0.75 = 39.75

$><<(<<2*2+?2)[eval gets]
$><<(<<2*2+?2)[eval gets]
2

Generates a HEREDOC string delimited by a 2 on its own line, concatenates it (*2) and then adds in the final 2 via a character literal. Slices into it using Ruby's built in String#[], which supports positive integers, negative integers, and ranges (input in the form m..n). $><< is output. (puts would require an extra space here).

Answer 6

Ruby, 38.25 bytes

a="a=%p;$><<(a%%a)[eval gets]";$><<(a%a)[eval gets]

Support negative indices and ranges. I blatantly picked up both $><< and the eval trick from histocrat, and the quine trick was someone else's to begin with, so I'll make this CW.

Answer 7

Python 2, 46.55 bytes

a="a=%r;print(a%%a)[input()]";print(a%a)[input()]

Supports negative indices.

Answer 8

Haskell, 122 bytes

main=getLine>>= \i->putChar$(!!(read i))$p++show p where p="main=getLine>>= \\i->putChar$(!!(read i))$p++show p where p="

Ungolfed:

main=getLine>>= \i->putChar$(!!(read i))$p++show p
 where p="main=getLine>>= \\i->putChar$(!!(read i))$p++show p\n where p="

Answer 9

Befunge 93, 5 bytes

This is pretty (very) late but I'll post it anyway:

&0g,@