Five programming problems every Software Engineer should be able to solve in less than 1 hour

[Geoff Canyon]

I rewrote the function to take arbitrary arguments for the list of numbers
and the target value, and then took advantage of the fact that char 0 of
"+-" is empty:

function problem5 S,T
   local tResults
   local countLessOne
   local tScheme
   local tSum
   split S using comma
   put (item 2 of the extents of S) - 1 into countLessOne
   repeat with i = 0 to 3^(countLessOne)
      put empty into tSum
      put format("%0" & countLessOne & "s", baseConvert(i, 10, 3)) into
tScheme
      repeat with j = 1 to countLessOne
         put S[j] & char (char j of tScheme) of "+-" after tSum
      end repeat
      put S[countLessOne + 1] after tSum
      if value(tSum) is T
      then put tSum & return after tResults
   end repeat
   return tResults
end problem5

On Sun, May 10, 2015 at 10:21 AM, Geoff Canyon <gcanyon at gmail.com> wrote:

>
> On Sun, May 10, 2015 at 5:38 AM, Mark Waddingham <mark at livecode.com>
> wrote:
>
>> ---- PROBLEM 5
>> ----   At first sight this one seems 'scary' but in actual fact the
>> ----   number of combinations is actually quite small (3^8) and you
>> ----   can get them by counting from 0 to 3^8 in ternery and padding
>> ----   the result to 8 digits. I then use 0 for no sign, 1 for + and
>> ----   2 for -. Having 'value' makes checking the sums trivial.
>>
>
> I thought briefly about doing this but it didn't gel in my mind as quickly
> as the substitution method I used. I quite like how this turned out!
>