38
1
It's simple: Make a proper quine where if you remove any character, it's still a quine.
The difference between this and a radiation hardened quine is that if your program is AB, in a radiation hardened quine A would output AB, but here, A would output A.
Code golf, all standard rules, standard loopholes apply, no cheating.
CalculatorFeline
Posted 2016-02-20T03:41:54.417
Reputation: 2 608
22
This answer uses ><>'s jumping instruction to fix the problem.
!<0078*+00~..>0[!."r43a*+8a+&{ee+00&1-:&(?.~~ol?!;4b*0.0f<>0['r3d*159*+&}7a*00&1-:&(?.~~ol?!;68a*+0.0+*a58
This quine actually contains two different quine generators. It starts with some jumping logic and by default uses the left quine. If a character is removed from the jumping logic or from the left quine, the program jumps to the right quine.
The code can be dissected into a few parts:
A: !<0078*+00~..>0[!.
B: >0[!."r43a*+8a+&{ee+00&1-:&(?.~~ol?!;4b*0.
C: .0f<
D: >0['r3d*159*+&}7a*00&1-:&(?.~~ol?!;68a*+0.
E: .0+*a58
Explanation of the different parts:
Once the instruction pointer reaches either of the quines, you're certain that that quine is completely intact.
>0[!. //Fix the instruction pointer's direction and empty the stack (The '!.' is a leftover from codepart A)
"r43a*+ //Start reading all of the code and add the '"' character to the stack
8a+& //Because the quine started reading at the 19th character instead of the first, the stack has to move 18 characters.
//This part saves the number 18 to the register.
{ee+00&1-:&(?. //Move the stack one to the left, decrease the stack by 1. If the stack is not empty yet, jump back to the start of this section.
~~ //Clean the temporary variables from the stack. It should now contain the whole quine.
ol?!;4b*0. //Print the first character from the stack. As long as the stack isn't empty, jump back to the start of this section.
Thijs ter Haar
Posted 2016-02-20T03:41:54.417
Reputation: 752
Explanation please. – CalculatorFeline – 2017-06-12T19:49:33.547
Reiterating above. – CalculatorFeline – 2017-06-22T03:53:42.373
1Is this clear enough? – Thijs ter Haar – 2017-06-22T08:09:13.873
36
It has this number of null characters:
453997365974271498471447945720930600149036031871190716908688344432973027776681259141680552038829875159204621651993092104775733418288411812715164994750890484868305218411129600012389568016974351721147925344946382782884546247102886167837964612372737300786173159265347137401863281368021545169383664534228503236761742285358985343373496184959796553930661837467682191561275123057706776367104142995491262443697167483190110516522677811931124842961701222425076750211774387637740969301686178545299089832300154448308384461700726890067468872402133010536518468336342175124002115991866466700174974019423711837589532744970385003356612639263433822126850314801275940879069069974437167102618471264140597777702065896715558989678487253830854848740247786166790545462769498303055791292
Seeing how the criterion in this challenge conflicts with the definition of a "proper quine", seriously, I think an Unary variant is going to win.
Expanded Brainfuck code:
>>+++>++++++++>+++>+++>+>+>+>+>+>+>+>+++>+>+>+>+>+>+>+>+>+++>+>+>+>+>+>+>+>+>++++++++>++++>++++++++>++++>+++++++>++>+++>+>+++>++>+++>+++>+>+>+>+>+>+>+>+>++++>++++>+++++++>+>++++>++++++++>++>+++++++>+++>++++++++>++>+++++++>+++>++++++++>++>+++++++>+++>++++++++>++>+++++++>+++>+++++>++++++++>++++>+++++++>+++++++>+>+>+++>+>+>+>++++++++>+++>+++++++>+>+++>+>+++>+>+++>+>++++++++>++++>++++++++>++++>++++++++>++++>++++>+>+++>+++>++>+++++++>+++++++>+>+>+>++++++++>+++>+>++++++++>++++>+>+++>++>+++++++>++>+++++++>++++>++++>++++++++>+++>++++++++>+++>+++>+>++++>++++>++>+++++++>+++>+++>++++++++>++++>+>+++>++>+++++++>++++>++++>+++++++>+++>+++>+++>+++>++++++++>++++>++++>+>+++>+>+++>++>+++++++>+++++++
[
[->+>+<<]
>>>>[<<[->+<]>>[-<<+>>]>]
<<[-[->+<]+>]+++
[[->>+<<]<]<
]
+>+>+>+
[>]+++>++
[
[<].
>[-]>[-]>[-]>[-]
<+[<<++++++++>>->+>-[<]<]
++++++++>++++++++>+++++++>>
]
.
If one character is removed from the Lenguage program, the last character becomes a <, which causes the program to print exactly one less character.
jimmy23013
Posted 2016-02-20T03:41:54.417
Reputation: 34 042
1How did you manage to find that fixed point? (Or alternatively, how does the Brainfuck code work?) – Martin Ender – 2016-02-21T09:54:38.097
1@MartinBüttner The first big loop copies and encodes the data in the form of ">+++..." (and reverses it). The other big loop print the data as an integer in unary. It's not that complicated but is long only because it's Brainfuck. – jimmy23013 – 2016-02-21T11:11:56.923
Oh right, so it's just like a plain Brainfuck quine, but with a different decoding function? – Martin Ender – 2016-02-21T11:13:16.610
@MartinBüttner Somewhat. But half of the program is the "decoding function". – jimmy23013 – 2016-02-21T11:17:08.993
It seems you could use a similar technique to construct answers of arbitrary score for http://codegolf.stackexchange.com/q/57257/8478 (although how exactly that works would depend on the answer to my latest comment).
– Martin Ender – 2016-02-21T17:03:22.000@lirtosiast It is a true quine. The first line in the Brainfuck code encodes the rest. (Or the number of whole segments consisting of 8^155 null characters encodes other null characters, if you prefer that.) – jimmy23013 – 2016-02-21T22:00:52.857
@MartinBüttner Technically, it says the program should work only when exactly n characters are removed, but not less, so you can get an arbitrary n. But still, it says least program_length^2/n wins, where a long program like this doesn't have much advantage. – jimmy23013 – 2016-02-21T22:12:21.473
@jimmy23013 yeah, the scoring was changed after my comment. – Martin Ender – 2016-02-21T22:14:05.223
@MartinBüttner Last time I checked it I believed that it must also work if less than n characters are removed. In that case it can only get a score of 3, or the final character would become an unmatched ], making the program invalid. – jimmy23013 – 2016-02-21T22:21:12.370
How would one include a payload on this quine? – lirtosiast – 2016-02-21T22:58:21.953
@lirtosiast Insert code before the second loop in the Brainfuck code. The memory is the Brainfuck code with the instructions represented by 1 to 8, with some delimiters. – jimmy23013 – 2016-02-21T23:06:08.973
Is an empty program valid? – Loovjo – 2016-02-20T07:06:43.570
4
@Loovjo No.
– Martin Ender – 2016-02-20T09:55:36.107Does the original program need to be a quine? I.e. in the example, is it enough that
AoutputsAandBoutputsB, or is it also necessary thatABoutputsAB? – feersum – 2016-02-21T04:26:50.2333@feersum The challenge states "Make a quine where...", so
ABshould outputAB. – Mego – 2016-02-21T04:54:27.0371@Mego I know it says that, but specifications are not always so precise, and it is not indicated in the examples. – feersum – 2016-02-21T05:20:54.637
4@feersum "Make a quine" means make a quine. "The difference between this and a radiation-hardened quine..." means that the only difference is that the program with any one byte removed results in a quine, not a program that prints the original program's source. There is no ambiguity here. – Mego – 2016-02-21T05:24:34.063