Add UE1 A.2

This commit is contained in:
Ivaylo Ivanov 2021-10-15 19:30:29 +02:00
parent 44f00d0e7e
commit b1caccfe26
2 changed files with 41 additions and 21 deletions

View File

@ -1,3 +1,7 @@
FROM haskell:buster
RUN apt-get update && apt-get install -y haskell-platform
WORKDIR /opt
CMD ["ghci"]

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@ -16,9 +16,6 @@ type Zerlegungszeugen = [Zerlegungszeuge]
-- Aufgabe A.1
ist_tzr :: Zeichenreihe -> Teilzeichenreihe -> IstTeilzeichenreihe
{-
Solution:
- if both strings are the same, True
@ -29,26 +26,49 @@ ist_tzr :: Zeichenreihe -> Teilzeichenreihe -> IstTeilzeichenreihe
If it is not, the first string will get smaller than the second eventually and the function will return False
-}
ist_tzr x y
| y == x = True
| y == [] = True
| length y > length x = False
ist_tzr :: Zeichenreihe -> Teilzeichenreihe -> IstTeilzeichenreihe
ist_tzr z t
| t == z = True
| t == [] = True
| length t > length z = False
| otherwise =
if head x == head y then
ist_tzr (tail x) (tail y)
if head z == head t then
ist_tzr (tail z) (tail t)
else
ist_tzr (tail x) y
ist_tzr (tail z) t
-- Aufgabe A.2
--tzr_zeuge :: Zeichenreihe -> Teilzeichenreihe -> Zerlegungszeuge
{- Knapp, aber gut nachvollziehbar geht tzr_zeuge folgendermassen vor:
...
{-
Solution:
- the base cases are as follows:
- both strings are empty, return a triple with empty strings
- the second string is empty, return a triple with empty strings as first two elements and the whole first string as a third.
The problem description states that the split doesn't matter, so we take this because it is easy and cheap to do :)
- the second string is not a subset of the first string, return the "error triple"
- for handling the other cases:
- we find the position of the last subset string in the first string
- we take all of the characters until this position - this is the first element of the triple
- we then take all of the characters after this position summed with the length of the second string - this is the third element of the triple
-}
tzr_zeuge :: Zeichenreihe -> Teilzeichenreihe -> Zerlegungszeuge
tzr_zeuge [] [] = ("", "", "")
tzr_zeuge z [] = ("", "", z)
tzr_zeuge z t
| not (ist_tzr z t) = ("", t ++ t, "")
| otherwise =
let pos = (find_tzr_position z t 0) - 1
pre = take (pos) z
suf = drop (pos + (length t)) z
in (pre, t, suf)
-- find the index of the last occurrence of t in z
find_tzr_position :: Zeichenreihe -> Teilzeichenreihe -> Nat0 -> Nat0
find_tzr_position (z:zs) t n
| not (ist_tzr (z:zs) t) = n
| otherwise = find_tzr_position zs t (n + 1)
-- Aufgabe A.3
--tzr_zeugen :: Zeichenreihe -> Teilzeichenreihe -> Zerlegungszeugen
@ -65,7 +85,3 @@ ist_tzr x y
{- Knapp, aber gut nachvollziehbar geht wieOft folgendermassen vor:
...
-}