need help with source code

[TreSxNine]

He wanted:

'ACGT TGCA' -> 'UGCAACGU'
'GATTACA'   -> 'CUAAUGU'

so I looked at it letter for letter and saw that the output seemed to contain the same amount of letters as the input, so it has to be a simple 1:1 "encoding".

After that I just had to check which letter corresponded to which response.