Find missing element in an array.

RE: Find missing element in an array.

ankitr851905 — Mon, 22 May 2023 17:00:50 GMT

a!localVariables(
local!number: { 1, 2, 3,4,5,7},
local!n: length(local!number) ,
((local!n +1) *(local!n+2))/2 - sum(local!number),

)

RE: Find missing element in an array.

davel001150 — Mon, 22 May 2023 13:23:47 GMT

I'd say this is the best approach except that I would go by length of the array +1, rather than by max value. That eliminates the possibility of tripping up on first value or last value. But I was totally about to bust out a!forEach.

Plus I never knew that 1 + enumerate(n) worked; I always did enumerate(n) +1. Still trying to decide which is more readable.

RE: Find missing element in an array.

Peter Lewis — Mon, 22 May 2023 12:49:50 GMT

Just swap max(local!list) with your actual maximum number - try this:

a!localVariables(
  local!maxNumber: 6,
  local!list: {1, 2, 3, 4, 5},
  difference(1 + enumerate(local!maxNumber), local!list)
)

RE: Find missing element in an array.

Amaan Shekh — Mon, 22 May 2023 04:17:23 GMT

this code will not work for {1,2,3,4,5} where N = 6 or for similar cases

RE: Find missing element in an array.

Amaan Shekh — Mon, 22 May 2023 04:10:06 GMT

alternate approach ->

a!localVariables(
  local!list: { 1, 2, 3, 4, 5, 6, 9, 8, 10, 11 },
  local!n: length(local!list) + 1,
  (local!n * (local!n + 1)) / 2 - sum(local!list)
)

RE: Find missing element in an array.

Stefan Helzle — Sun, 21 May 2023 12:23:12 GMT

a!localVariables(
  local!list: {1,2,3,5},
  difference(1 + enumerate(max(local!list)), local!list)
)