caesar 2 and pythagoras 2 (no tests)

Co-authored-by: KaloyanStoykov <KaloyanStoykov@users.noreply.github.com>

wk2/elm.json

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+{
+    "type": "application",
+    "source-directories": [
+        "src"
+    ],
+    "elm-version": "0.19.1",
+    "dependencies": {
+        "direct": {
+            "elm/browser": "1.0.2",
+            "elm/core": "1.0.5",
+            "elm/html": "1.0.0"
+        },
+        "indirect": {
+            "elm/json": "1.1.3",
+            "elm/time": "1.0.0",
+            "elm/url": "1.0.0",
+            "elm/virtual-dom": "1.0.3"
+        }
+    },
+    "test-dependencies": {
+        "direct": {},
+        "indirect": {}
+    }
+}

wk2/src/Caesar2.elm

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+module Caesar2 exposing (..)
+
+{-
+    Caesar cipher (Part 2)
+    Dimitar Byalkov and Kaloyan Stoykov
+-}
+
+encode: Int -> Char -> Char
+encode offset character =
+    -- Char.isUpper replaces the check for the ASCII code range of uppercase letters
+    if Char.isUpper character then
+        shiftChar (Char.toCode 'A') offset character
+    -- Char.isLowe replaces the check for the ASCII code range of lowercase letters
+    else if Char.isLower character then
+        shiftChar (Char.toCode 'a') offset character
+    else ' '
+
+-- shiftChar takes the common arithmetic actions from the if-statement in 'encode'
+shiftChar: Int -> Int -> Char -> Char
+shiftChar baseCode offset character =
+    Char.fromCode(baseCode + modBy 26 ((Char.toCode character) - baseCode + offset - 26))
+
+decode: Int -> Char -> Char
+decode offset character = 
+    encode (0 - offset) character
+
+normalize: String -> String
+normalize input =
+    String.fromList (List.filter Char.isAlpha (String.toList input))
+
+encrypt: Int -> String -> String
+encrypt offset input = 
+    case String.uncons input of
+        Nothing ->
+            ""
+        Just (head, tail) ->
+            String.cons (encode offset head) (encrypt offset tail)
+
+decrypt: Int -> String -> String
+decrypt offset input = 
+    case String.uncons input of
+        Nothing ->
+            ""
+        Just (head, tail) ->
+            String.cons (decode offset head) (decrypt offset tail)

wk2/src/Pythagoras2.elm

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+module Pythagoras2 exposing (..)
+
+{-  
+    Pythagoraen triples (Part 2)
+    Dimitar Byalkov and Kaloyan Stoykov
+-}
+
+pythTriplesMap: List (Int, Int) -> List (Int, Int, Int)
+pythTriplesMap input =
+    List.map pythTriple input
+
+pythTriplesRec: List (Int, Int) -> List (Int, Int, Int)
+pythTriplesRec input = 
+    -- We have a base case for an empty list which stops the recursion.
+    case input of 
+        [] ->
+            []
+        {- We take out the first element x of the list and 
+           we are left with the rest of the list - xs, which we use to recursively call the function -}
+        x :: xs ->
+            List.singleton (pythTriple x) ++ pythTriplesRec xs
+
+
+-- Taken and condensed from Pythagoras, part 1
+pythTriple: (Int, Int) -> (Int, Int, Int)
+pythTriple (x, y) =
+    if x < 0 || y < 0 then
+        (0, 0, 0)
+    else
+        ((x ^ 2 - y ^ 2), (2 * y * x), (x ^ 2 + y ^ 2))
+
+{- 
+    Taken from Pythagoras, part 1
+    Checks if the three numbers form a Pythagorean triple
+-}
+isTriple: Int -> Int -> Int -> Bool
+isTriple a b c =
+    if a <= 0 || b <= 0 || c <= 0 then
+        False
+    else if (a ^ 2 + b ^ 2) /= c ^ 2 then
+        False
+    else True
+
+-- check a give triple tuple forms a Pythagorean triple
+isTripleTuple : (Int, Int, Int) -> Bool
+isTripleTuple (a, b, c) = 
+    isTriple a b c
+
+arePythTriplesFilter: List (Int, Int, Int) -> List (Int, Int, Int)
+arePythTriplesFilter tripleList =
+    List.filter isTripleTuple tripleList
+
+arePythTriplesRec: List (Int, Int, Int) -> List (Int, Int, Int)
+arePythTriplesRec tripleList = 
+    case tripleList of 
+        [] ->
+            []
+        x :: xs ->
+            if isTripleTuple x then
+                List.singleton x ++ arePythTriplesRec xs
+            else
+                arePythTriplesRec xs