About javascript looping logic

JavaScript
1

Let car = [‘c’,‘a’,‘r’];

Expected result: [‘c’,‘ca’,‘cr’,‘car’,‘a’,‘ar’,‘r’]

How to solve this by forloop in js?

Thanks in advance

2

What have you tried so far?

3

Gonna be honest, the answer to this using for is somewhat eluding me… at least, in the expected result order.

4

Solved . . .

3 Likes
5

Somehow Virgil comes to mind on looking at that.

“Beware of Greeks bearing gifts.” - Virgil.

2 Likes
6

I have just used split to seperate it and concat

I want to know if it’s possible using forloop

7

Amusing.

I can get to a point where it would give [“c”,“a”,“r”,“ca”,“cr”, “ar”,“car”] in a relatively non-specific for formation, but not in the order that was given.

Essentially, OP would be hardcoding a recursive operation though, which is the better solution.

11

Order is not an issue

12

Less ‘if’ statements now . . . . .

13

OP, is there an actual problem you are trying to solve by doing this?

2 Likes
14

Well then this should do the trick…

function powerset ([head, ...tail]) {
  if (!head) {
    return []
  }

  if (!tail.length) {
    return [head]
  }

  const tailResults = powerset(tail)

  return [head, ...tailResults, ...tailResults.map(
    result => head + result)]
}

console.log(powerset(['c', 'a', 'r'])) // ['c', 'a', 'r', 'ar', 'ca',  'cr', 'car']

BTW does anyone know the technical term for this?

Edit: Thx @rpkamp! :-)

15

That will be combinations. The other one commonly seen is permutations.

[Edit: Cunningham’s Law to the rescue once again!
“the best way to get the right answer on the internet is not to ask a question; it’s to post the wrong answer.”]

1 Like
16

It’s the Power set of the set (“c”, “a”, “r”)

3 Likes
17

strictly speaking if it was a power set it would also contain "", (a power set contains 2^n elements, so an input set of size 3 should have a power set of size 8) but thats a quibble. :stuck_out_tongue:

1 Like
18

This topic was automatically closed 91 days after the last reply. New replies are no longer allowed.