Ways to add 1 to lists of lists

Question

Adapted from this StackOverflow question

In this challenge you will take a list of lists of integers, e.g.

A = [[1,2],[3,4],[5],[]]

And an additional single integer (e.g. n = 7). If you were to add n to the front of one of the lists in A there would be as many ways to do that as there are lists in A. In this example 4:

A' = [[7,1,2],[3,4],[5],[]] A' = [[1,2],[7,3,4],[5],[]] A' = [[1,2],[3,4],[7,5],[]] A' = [[1,2],[3,4],[5],[7]]

In this challenge you will output all possible ways to do this, in the order of how early n is inserted. So for the example the output is just:

[ [[7,1,2],[3,4],[5],[]] , [[1,2],[7,3,4],[5],[]] , [[1,2],[3,4],[7,5],[]] , [[1,2],[3,4],[5],[7]] ]

This is codegolf so answer answers will be scored in bytes with fewer bytes being better.

Test cases

9, [] -> [] 9, [[]] -> [[[9]]] 10, [[1,2,3]] -> [[[10,1,2,3]]] 7, [[1,2],[3,4],[5],[]] -> [[[7,1,2],[3,4],[5],[]],[[1,2],[7,3,4],[5],[]],[[1,2],[3,4],[7,5],[]],[[1,2],[3,4],[5],[7]]] 2, [[1,2],[2,2],[2]] -> [[[2,1,2],[2,2],[2]],[[1,2],[2,2,2],[2]],[[1,2],[2,2],[2,2]]]

\$\begingroup\$ The lists aren't guaranteed to be unique, right? \$\endgroup\$

att
– att

2021-11-18 04:19:57 +00:00
Commented Nov 18, 2021 at 4:19 — att
– att, Commented Nov 18, 2021 at 4:19

Marston · Accepted Answer · 2021-11-18 19:32:38Z

Rust, 185 184 bytes

My first ever code golf submission

fn r(a:Vec<Vec<u8>>,n:u8){let mut x:Vec<Vec<Vec<u8>>>=Vec::new();for i in 0..a.len(){let mut b=a.clone();let c=&vec![n];b[i].splice(0..0,c.iter().cloned());x.push(b);}print!("{:?}",x)}

Explanation

This code copies the list for every sublist, then appends the number to the front of it, adds it to a final list which it then prints. We can also get away with returning the print statement to save a ;!

Try it online!

Edit: Kevin Cruijssen pointed out a space in my print.

Edit: @Bubbler showed me what it's like to truly golf in Rust and got it down to 90 bytes! I won't be updating the byte count in the header since I don't believe that his edits counts as "edits" rather an entire new submission and it doesn't reflect my work.

|a:&mut[Vec<_>],n|{for i in 0..a.len(){a[i].insert(0,n);print!("{:?}",a);a[i].remove(0);}}

Welcome to Code Golf, and nice first answer! Submissions are required to make a serious effort to meet the winning criteria as much as possible, in this case code-golf. You did a pretty good job of that already with short variable names and things like that, but you should make sure to also remove unnecessary whitespace. — Aaroneous Miller
– Aaroneous Miller, Commented Nov 17, 2021 at 17:21
No problem, glad to help! Also, I don't know personally know anything about Rust, but you should check out our tips for golfing in Rust to see if there are any other golfs you could use. Happy golfing! — Aaroneous Miller
– Aaroneous Miller, Commented Nov 17, 2021 at 17:24
With lots of type and output format fiddling, it is possible to get down to 98 bytes. — Bubbler
– Bubbler, Commented Nov 18, 2021 at 1:59

Kevin Cruijssen · Accepted Answer · 2021-11-17 14:11:07Z

05AB1E, 6 bytes

UεXšNǝ

Try it online or verify all test cases.

Explanation:

U # Pop the store the first (implicit) input-integer in variable `X` ε # Map over the second (implicit) input-list of lists: Xš # Prepend `X` in front of the current part Nǝ # And replace the item at the current map-index in the second (implicit) # input-list with this modified part # (after which the result is output implicitly)

2 revs · Accepted Answer · 2021-11-17 11:38:08Z

Haskell, 37 bytes

This is Willem Van Onsem's SO answer with a couple of trivial golfs.

n!(a:b)=((n:a):b):map(a:)(n!b) _!_=[]

Try it online!

Graham · Accepted Answer · 2021-11-17 18:43:56Z

APL+WIN, 36 bytes

Prompts for the list of lists as a nested vector then the integer to be added. Index origin = 0

m←((⍴n)*2)⍴n←,⎕⋄m[(1+⍴n)×⍳⍴n]←⎕,¨n⋄m

Try it online! Thanks to Dyalog Classic

Jonah · Accepted Answer · 2021-11-17 23:05:58Z

J, ^{22 17 21} 20 bytes

(<@#"0~[:=#\),&.>"1]

Try it online!

Could save 4 bytes if we can assume each element of the input is unique.

Consider 7 f 1 2 3; 1 2; 4:

[:=#\ Create an identity matrix whose sides equal our list length:
```
1 0 0 0 1 0 0 0 1 
```

<@#"0~ Use that as a mask to copy our new element, and box each result. Zeros become empty boxes:

┌─┬─┬─┐ │7│ │ │ ├─┼─┼─┤ │ │7│ │ ├─┼─┼─┤ │ │ │7│ └─┴─┴─┘

,&.>"1] For each row, join elementwise to the original input:

┌───────┬─────┬───┐ │7 1 2 3│1 2 │4 │ ├───────┼─────┼───┤ │1 2 3 │7 1 2│4 │ ├───────┼─────┼───┤ │1 2 3 │1 2 │7 4│ └───────┴─────┴───┘

tsh · Accepted Answer · 2021-11-18 01:46:17Z

3

JavaScript (Node.js), 41 bytes

t=>a=>a.map(u=>a.map(v=>u==v?[t,...u]:v))

Try it online!

answered Nov 18, 2021 at 1:46

tsh

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alephalpha · Accepted Answer · 2021-11-18 07:59:34Z

3

Wolfram Language (Mathematica), 31 bytes

(i=1;x##~Insert~{i++,1})/@#&

Try it online!

answered Nov 18, 2021 at 7:59

alephalpha

51.9k7 gold badges75 silver badges197 bronze badges

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lyxal · Accepted Answer · 2023-11-21 01:13:08Z

3

Vyxal, 54 bits^v2, 6.75 bytes

vJ¨2¹^Ȧ

Try it Online!

Bitstring:

100010101100011111000100110100010110110111100010110010

edited Nov 21, 2023 at 1:13

answered Nov 17, 2021 at 11:38

lyxal♦

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\$\begingroup\$ Alternate 9 byter \$\endgroup\$

Aaroneous Miller
– Aaroneous Miller

2021-11-17 15:35:01 +00:00
Commented Nov 17, 2021 at 15:35

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chunes · Accepted Answer · 2023-11-21 02:44:45Z

Uiua, 13 12 bytes

≡⍜(⇌⊔⊡)⊂⇡⊃⧻¤

Try it!

-1 thanks to Bubbler

≡⍜(⇌⊔⊡)⊂⇡⊃⧻¤ ⊃⧻¤ # fix the array and get its length ⇡ # range (of length) ≡⍜(⇌⊔⊡) # change each unboxed reversed row by... ⊂ # join (the integer input) # then unreverse, re-box, and put each item back

\$\begingroup\$ ⍜⊡(□⊂:⊔) -> ⍜(⇌⊔⊡)⊂ to save 1. \$\endgroup\$

Bubbler
– Bubbler

2023-11-21 01:53:14 +00:00
Commented Nov 21, 2023 at 1:53 — Bubbler
– Bubbler, Commented Nov 21, 2023 at 1:53
\$\begingroup\$ @Bubbler Clever, thanks! \$\endgroup\$

chunes
– chunes

2023-11-21 02:36:12 +00:00
Commented Nov 21, 2023 at 2:36 — chunes
– chunes, Commented Nov 21, 2023 at 2:36

Neil · Accepted Answer · 2021-11-17 12:14:39Z

Retina, 33 bytes

L$`\[+(?=(.+),(.+)) $>`$2,$1 ,] ]

Try it online! Takes n as the second argument. Explanation:

L$`\[+(?=(.+),(.+))

Find the beginning of each list.

$>`$2,$1

For each occurrence, output the list with n moved to that position.

,] ]

Fix up the list if it was originally empty.

loopy walt · Accepted Answer · 2021-11-17 12:45:50Z

Python 3, 50 bytes

lambda a,L:[[[a][:l is k]+l for l in L]for k in L]

Try it online!

Will not work on lists with multiple references to the same object. I..e.: L = [[10],[10]] fine (same value but different objects) but L = 2*[[10]] fail (twice the same object)

pajonk · Accepted Answer · 2021-11-17 13:34:00Z

R, 58 bytes

Or R>=4.1, 44 bytes by replacing two function occurrences with \s.

function(x,A)Map(function(i){A[[i]]=c(x,A[[i]]);A},seq(A))

Try it online!

MarcMush · Accepted Answer · 2021-11-17 16:44:21Z

2

Julia 1.0, 47 bytes

n\l=(k=keys(l)).|>i->k.|>j->[fill(n,i==j);l[j]]

Try it online!

answered Nov 17, 2021 at 16:44

MarcMush

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AZTECCO · Accepted Answer · 2021-11-17 22:51:55Z

2

Ruby, 60 bytes

->n,l{(0...t=l.size).map{|i|[*l[0,i],[n]+l[i],*l[i+1...t]]}}

Try it online!

answered Nov 17, 2021 at 22:51

AZTECCO

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G B · Accepted Answer · 2021-11-18 06:56:46Z

2

Ruby, 42 bytes

->n,l{i=-1;l.map{|w|z=*l;z[i+=1]=[n]+w;z}}

Try it online!

answered Nov 18, 2021 at 6:56

G B

23.4k1 gold badge24 silver badges55 bronze badges

\$\begingroup\$ ->n,l{i=-1;l.map{z=*l;z[i+=1]=[n]+_1;z}} to save 2 bytes \$\endgroup\$

Wezl
– Wezl

2021-11-20 14:18:04 +00:00
Commented Nov 20, 2021 at 14:18

Add a comment |

ZippyMagician · Accepted Answer · 2021-11-19 18:50:45Z

ayr, 15 bytes

Beats J by 5 bytes, so I'm happy :)

],`"\:]:#":i:&#

Explanation

 i:&# Construct an NxN identity matrix (N = # lists) #": Foreach num I in that, replace with left arg I times ]: Convert that to a hook \: For each item on the right and entirety of left ,`" Concatenate left to back of right on an element x element basis ] Where the left is the list

Takes the number on the left and the list of lists on the right.

customcommander · Accepted Answer · 2021-11-24 01:26:51Z

2

jq, 51 bytes

. as$a|[range(length)]|map(. as$i|$a|.[$i]|=[$n]+.)

Where $n is n.

answered Nov 24, 2021 at 1:26

customcommander

2702 silver badges9 bronze badges

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alephalpha · Accepted Answer · 2023-11-21 01:23:48Z

2

Curry (PAKCS), 21 bytes

n!(a++b:c)=a++(n:b):c

Attempt This Online!

answered Nov 21, 2023 at 1:23

alephalpha

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Neil · Accepted Answer · 2021-11-17 12:09:31Z

Charcoal, 16 bytes

ＩＥηＥη⎇⁼κμ⮌⊞Ｏ⮌λθλ

Try it online! Link is to verbose version of code. Explanation:

 η Input list of lists Ｅ Map over each list η Input list of lists Ｅ Map over each list κ Outer index ⁼ Equal to μ Inner index ⎇ If true then λ Current list ⮌ Reversed θ Input `n` ⊞Ｏ Appended ⮌ Reversed λ Otherwise current list Ｉ Cast to string Implicitly print

Charcoal's default output format might be a little tricky to read, so here's a 17-byte version with prettier output:

Ｅη⭆¹Ｅη⎇⁼κξ⮌⊞Ｏ⮌νθν

Try it online! Link is to verbose version of code.

Arnauld · Accepted Answer · 2021-11-18 01:24:28Z

JavaScript (ES6), 44 bytes

Expects (n)(list_of_lists).

Version 1

n=>a=>a.map((v,i,[...b])=>(b[i]=[n,...v],b))

Try it online!

Version 2

n=>a=>a.map((_,i)=>a.map(v=>i--?v:[n,...v]))

Try it online!

alephalpha · Accepted Answer · 2021-11-18 08:08:02Z

1

Pari/GP, 48 bytes

(n,a)->matrix(#a,,i,j,concat([n][1..i==j],a[j]))

Try it online!

edited Nov 18, 2021 at 8:08

answered Nov 17, 2021 at 12:27

alephalpha

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DLosc · Accepted Answer · 2022-03-24 00:56:24Z

Pip `-xP`, 13 bytes

aRA_(BPEb)MEa

Attempt This Online!

Explanation

The -x flag evaluates the inputs, meaning we can treat [[1];[2;3]] as a list rather than a string.

aRA_(BPEb)MEa a First command-line input (the nested list) ME Map the following function to that list, enumerated (first function arg is index, second function arg is sublist): a The whole list RA Replace the element at index given by _ first function arg ( ) with B second function arg PE with the following value prepended: b Second command-line input

The -P flag prints each sublist of the result, formatted as a list, on a separate line. Other formats that could work include -p and -S.

DeathIncarnate · Accepted Answer · 2021-11-19 16:25:28Z

Burlesque, 24 bytes

1svsa.*zi{{1gv+]}x/ap}^m

Try it online!

I'm sure there's a better way...

1sv # Save input as 1 sa.* # Repeat arr len(arr) times zi # Zip with indices { { 1gv # Get input (value1) +] # Prepend } x/ # Reorder local stack ap # Apply function to index (from zip) }^m # Push and map each

Razetime · Accepted Answer · 2021-11-20 04:01:44Z

0

Stax, 10 bytes

ü↨○◘╞Q┐p☺Ç

Run and debug it

answered Nov 20, 2021 at 4:01

Razetime

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chunes · Accepted Answer · 2024-05-16 19:53:03Z

0

Arturo, 46 bytes

$[x,a][i:0map a=>[n:new a,n\[i]:@[x]++&'i+1n]]

Try it

answered May 16, 2024 at 19:53

chunes

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Stack Exchange Network

Ways to add 1 to lists of lists

Test cases

25 Answers 25

Rust, 185 184 bytes

05AB1E, 6 bytes

Haskell, 37 bytes

APL+WIN, 36 bytes

J, ^{22 17 21} 20 bytes

JavaScript (Node.js), 41 bytes

Wolfram Language (Mathematica), 31 bytes

Vyxal, 54 bits^v2, 6.75 bytes

Uiua, 13 12 bytes

Retina, 33 bytes

Python 3, 50 bytes

R, 58 bytes

Julia 1.0, 47 bytes

Ruby, 60 bytes

Ruby, 42 bytes

ayr, 15 bytes

Explanation

jq, 51 bytes

Curry (PAKCS), 21 bytes

Charcoal, 16 bytes

JavaScript (ES6), 44 bytes

Version 1

Version 2

Pari/GP, 48 bytes

Pip `-xP`, 13 bytes

Explanation

Burlesque, 24 bytes

Stax, 10 bytes

Arturo, 46 bytes

Linked

Hot Network Questions

Ways to add 1 to lists of lists

Test cases

25 Answers 25

Rust, 185 184 bytes

05AB1E, 6 bytes

Haskell, 37 bytes

APL+WIN, 36 bytes

J, 22 17 21 20 bytes

JavaScript (Node.js), 41 bytes

Wolfram Language (Mathematica), 31 bytes

Vyxal, 54 bitsv2, 6.75 bytes

Uiua, 13 12 bytes

Retina, 33 bytes

Python 3, 50 bytes

R, 58 bytes

Julia 1.0, 47 bytes

Ruby, 60 bytes

Ruby, 42 bytes

ayr, 15 bytes

Explanation

jq, 51 bytes

Curry (PAKCS), 21 bytes

Charcoal, 16 bytes

JavaScript (ES6), 44 bytes

Version 1

Version 2

Pari/GP, 48 bytes

Pip -xP, 13 bytes

Explanation

Burlesque, 24 bytes

Stax, 10 bytes

Arturo, 46 bytes

Linked

Related

Hot Network Questions

J, ^{22 17 21} 20 bytes

Vyxal, 54 bits^v2, 6.75 bytes

Pip `-xP`, 13 bytes