Determine if an Array contains something other than 2

Question

Take an array which consists of positive integers or arrays, output if it only contains 2s.

Output should be a truthy or falsey value (Sorry if this destroys answers)

Truthy Test Cases

[2]
[2,2]
[[2],[2,2],2]
[]
[[],[]]

Falsey Test Cases

[1]
[22]
[2,2,2,1]
[[1,2],2]

Standard Loopholes Are forbidden.

Default IO rules apply.

Code-golf, Fewest bytes wins!

• Wheat Wizard: Can we take in a string representing the array?
• Wheat Wizard: Will there be objects other than numbers and other arrays in the arrays
• user58988: What kind of numbers? Compex int, compex float, float int, int , not negative?
• ceased to turn counterclockwis: FTR and in the name of proper mathematical thinking: the array [[2]] does not contain a two.
• ATaco: @KevinCruijssen Given the sheer number of answers that ignore the commented restriction (And the age of the challenge), I'd rather now state that answers needn't worry about numbers other than positive integers. I'll adjust the challenge description to specify this.

Answer 1

Python 2, (削除) 44 (削除ここまで) (削除) 43 (削除ここまで) 42 bytes

Takes x as the string representation of the list. This also assumes like in the example the representations have no spaces.

lambda x:set(x)<=set("[],2"*0**("22"in x))

Try it online!

---

Explanation

Both of these take the characters in the string representation of the input and determine if any characters other than [], 2 are in it. They do this by casting to a set and comparing to the set of just those characters. However this fails if we have a number other than 2 which has only digits of 2 (e.g. 22 or 222), in order to patch this case we multiply the string used to create the set by the negation of whether or not x contains "22". If it contains it this will be the empty set, otherwise it will be the same as before.

• Leaky Nun: lambda x:set(x)==set("[], 2")?
• Leaky Nun: Fails for [22]
• Wheat Wizard: @LeakyNun Fixed
• Wheat Wizard: @LeakyNun Your suggestion fails for []
• ovs: lambda x:set(x)<=set("[],2"*-~-("22"in x)) for -1

Answer 2

Ohm, 6 bytes

∙e]Å2N

Uses CP-437 encoding.

Explanation:

∙e]Å2E
∙e ■しかくEvaluate the input to form an array
 Å ■しかくany( , )
 ] ■しかく flatten(input)
 2N ■しかく lambda x:x!=2
 ■しかくimplict end of any and print

Answer 3

PHP, 46 bytes

<?=!preg_match('/:"(?!2")/',serialize($_GET));

• user63956: @JörgHülsermann Could you please give an example? All the test cases seem to work. If you test it not through a browser, do you pass scalar values of $_GET as strings?
• Jörg Hülsermann: <?=!preg_match('/:"(?!2")/',$argn); and input is a string representation of the serialized array - 11 Bytes

Answer 4

PHP<7.0, 29 Bytes

Input as as string array JSON encoded

<?=!ereg("22|[013-9]",$argn);

PHP<7.0, 42 Bytes

use the deprecated function ereg

<?=!ereg("22|[013-9]",json_encode($_GET));

PHP, 50 Bytes

prints 1 for true and nothing for false

-1 Byte for other wise remove !

or + 1 Byte for true 1, false 0 add + before !

<?=!preg_match('#22|[013-9]#',json_encode($_GET));

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• user63956: You don't need the $r variable: <?array_walk_recursive($_GET,function($i){$i-2&&die;})?>1.

Answer 5

Pyth, 6 bytes

!-.nQ2

Very similar to my CJam answer. I'm still new to Pyth, so please tell me if there's anything I can golf off.

Explanation:

 Q Input: [[[], [2]], [1]]
 .n Flatten: [2, 1]
 - 2 Remove 2s: [1]
! Not: False

Answer 6

Ruby 1.9+, 19 bytes

->x{x*$/!~/^2?+.$/}

Form is stolen from G B's answer. The main difference is that I join on a newline (the default value of $/), which lets me write a shorter regex by using the ^.$ special characters that have specific interactions with newlines.

The trick that makes this version-specific (1.9 and higher) is the use of the "possessive" quantifier 2?+. Like 2?, it'll match zero or one instances of a 2, but this form will hold onto that 2 forever and prevent it from being matched by the ., so a 2 on its own line won't match the overall regexp.

Answer 7

Kotlin, 90 bytes

Submission

fun r(i:String):Any{return i.replace(Regex("[\\[\\]2,]+"),"")==""&&!i.contains("22")}

TryItOnline

TryItOnline

Answer 8

Japt -!, (削除) 6 (削除ここまで) (削除) 5 (削除ここまで) 4 bytes

c dÍ

Try it

c dÍ :Implicit output of array
c :Flatten
 d :Any truthy (non-zero) when
 Í :Subtracted from 2
 :Implicit output of negation of result

Answer 9

Vyxal, 3 bytes

2J≈

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Append a 2, check if everything is equal

Answer 10

Raku, 13 bytes

*.flat.all==2

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Answer 11

Uiua, 8 bytes

×ばつ=2

Try it!

×ばつ=2
 =2 # where are elements equal to two?
 ×ばつ # multiply columns, filling missing elements with one×ばつ # product

Answer 12

Setanta, 84 bytes

gniomh f(l){ma go_teacs(l)<"[" toradh l==2t:=1le i idir(0,fad@l)t=t&f(l[i])toradh t}

try-setanta.ie link

Alternate text substitution-based solution, 93 bytes

gniomh(l){l=go_teacs(l)le i idir(0,5)l=athchuir@l(["[2",", 2","[","]",","][i],"")toradh"!">l}

Turns out to be longer than the recursion-based solution, but I think this is neat.

try-setanta.ie link

Answer 13

Clojure, 21 or 25 bytes

#(every?(set"[]2 ")%)
#(every? #{2}(flatten %))

The first one takes the argument as string, second one as an actual nested list.

#{2} is the set with one element 2, calling it with an existing element returns it and for a non-existing it returns nil (falsy).

Answer 14

Axiom, 280 bytes

w(x:Union(List(Any),NNI)):Boolean==(x case List(Any)=>(g:List(Any):=x;leaf? g=>return true;for i in g repeat(q:=w(i);q=false=>return false);return true);r:NNI:=x;r=2=>true;false)
m(b:List Any):Boolean==(for i in b repeat(q:=w(i::Union(List(Any),NNI));q=false=>return false);true)

ungolfed and test

f(x:Union(List(Any),NNI)):Boolean==
 x case List(Any)=>
 g:List(Any):=x
 leaf? g =>return true
 for i in g repeat 
 q:=f(i)
 q=false => return false
 return true
 r:NNI:=x
 r=2=>true
 false
h(b:List Any):Boolean==
 for i in b repeat
 q:=f(i::Union(List(Any),NNI))
 q=false=> return false
 true
(5) -> [[i, m(i)] for i in [ [2],[2,2],[[2],[2,2],2],[],[[],[]] ] ]
 (5)
 [[[2],true],[[2,2],true],[[[2],[2,2],2],true],[[],true],[[[],[]],true]]
 Type: List List Any
(6) -> [[i, m(i)] for i in [ [1],[22],[2,2,2,1], [[1,2],2] ] ]
 (6) [[[1],false],[[22],false],[[2,2,2,1],false],[[[1,2],2],false]]
 Type: List List Any

Answer 15

CJam, 7 bytes

Input is in the form of a CJam array literal.

q~e_2-!

Explanation:

q e# Read input: | "[[1 2] 2]"
~ e# Eval: | [[1 2] 2]
e_ e# Flatten: | [1 2 2]
2- e# Remove 2s: | [1]
! e# Not: | 0

Answer 16

Actually, 10 bytes

⌠♂i⌡Y2#@-b

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Explanation:

⌠♂i⌡Y2#@-b
⌠♂i⌡Y call the function until the result stops changing (fixed-point combinator):
 ♂i for each item: flatten
 2#@- set difference: all items that are not 2s
 b cast to boolean (1 if list is not empty, else 0)

Answer 17

Perl 5, 26 bytes

25 bytes of code + 1 for -n

map$.&=$_==2,/\d+/g;say$.

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Answer 18

TXR Lisp, 30 bytes

(opip flatten(all @1(op = 2)))

Run:

1> (opip flatten(all @1(op = 2)))
#<intrinsic fun: 0 param + variadic>
2> [*1 '()]
t
3> [*1 '(2)]
t
4> [*1 '(2 2 ())]
t
5> [*1 '(() ())]
t
6> [*1 '(() (1))]
nil
7> [*1 '((2) 1 ())]
nil

Answer 19

MY, 6 bytes

⎕ḟ2=Π←

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How?

• ⎕ evaluated input
• ḟ flatten
• 2= element-wise equality with two
• Π product
• ← output with no newline

Answer 20

Pyth, 6 bytes

q]2{.n

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Answer 21

Common Lisp, (削除) 68 (削除ここまで) 64 bytes

(defun n(l)(or(and(consp l)(n(car l))(n(cdr l)))(not l)(= l 2)))

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Answer 22

Jelly, (削除) 3 (削除ここまで) 4 bytes

F=2Ạ

Gained a byte because of a failed test case.

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• Ørjan Johansen: This fails on the [[1,2],2] test case.
• clapp: @ØrjanJohansen Fixed at the cost of one byte.
• steenbergh: It is now a dupe of this: codegolf.stackexchange.com/a/120371/44874

Answer 23

Arturo, 19 bytes

$=>[[]=--flatten&2]

Try it

$=>[ ; a function
 []= ; is the empty block equal to...
 --flatten&2 ; the input, flattened, with 2s removed?
] ; end function

Answer 24

Zsh, 9 bytes

<<<${@/2}

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Falsey: output contains a number. Truthy: anything else (spaces or empty string). Link includes a test harness that prints T or F

• Jo King: This doesn't really do nested lists does it? It just seems to be space separated numbers
• roblogic: True, Zsh only does 1-dimensional arrays/lists

Answer 25

Pyt, 4 bytes

Ƒ2=Π

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Ƒ implicit input; Ƒlatten array
 2= is each element equal to 2?
 Π product (returns 1 for empty array); implicit print

Answer 26

Fig, \3ドル\log_{256}(96)\approx\$ 2.469 bytes

r=2

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r=2
 =2 # Is each element equal to 2?
r # Product

Answer 27

APL(Dyalog Unicode), ^{(削除) (削除ここまで)}9 bytes ^SBCS

(⊢≡2⍴⍨≢)∊

Try it on APLgolf!

Alternatively, another 9-byte solution:

∧/'2 '∊⍨⍕

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Answer 28

AWK, 13 bytes

!/[013-9]|22/

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Will print line back to you for truthy, or nothing for falsey.