Kata

Your task is to add up letters to one letter.

The function will be given a variable amount of arguments, each one being a letter to add.

Notes:

• Letters will always be lowercase.
• Letters can overflow (see second to last example of the description)
• If no letters are given, the function should return 'z'

Examples:

addLetters('a', 'b', 'c') = 'f'
addLetters('a', 'b') = 'c'
addLetters('z') = 'z'
addLetters('z', 'a') = 'a'
addLetters('y', 'c', 'b') = 'd' // notice the letters overflowing
addLetters() = 'z'

addLetters('a', 'b', 'c') = 'f'
addLetters('a', 'b') = 'c'
addLetters('z') = 'z'
addLetters('z', 'a') = 'a'
addLetters('y', 'c', 'b') = 'd' // notice the letters overflowing
addLetters() = 'z'

addLetters('a', 'b', 'c') = 'f'
addLetters('a', 'b') = 'c'
addLetters('z') = 'z'
addLetters('z', 'a') = 'a'
addLetters('y', 'c', 'b') = 'd' // notice the letters overflowing
addLetters() = 'z'

addLetters('a', 'b', 'c') = 'f'
addLetters('a', 'b') = 'c'
addLetters('z') = 'z'
addLetters('z', 'a') = 'a'
addLetters('y', 'c', 'b') = 'd' # notice the letters overflowing
addLetters() = 'z'

add_letters('a', 'b', 'c') = 'f'
add_letters('a', 'b') = 'c'
add_letters('z') = 'z'
add_letters('z', 'a') = 'a'
add_letters('y', 'c', 'b') = 'd' # notice the letters overflowing
add_letters() = 'z'

add_letters(c('a', 'b', 'c')) = 'f'
add_letters(c('a', 'b')) = 'c'
add_letters(c('z')) = 'z'
add_letters(c('z', 'a')) = 'a'
add_letters(c('y', 'c', 'b')) = 'd' # notice the letters overflowing
add_letters(c()) = 'z'

add_letters('a', 'b', 'c') = 'f'
add_letters('a', 'b') = 'c'
add_letters('z') = 'z'
add_letters('z', 'a') = 'a'
add_letters('y', 'c', 'b') = 'd' # notice the letters overflowing
add_letters() = 'z'

{ "a" "b" "c" } add-letters ! "f"
{ "a" "b" } add-letters ! "c"
{ "z" } add-letters ! "z"
{ "z" "a" } add-letters ! "a"
{ "y" "c" "b" } add-letters ! "d" ! notice the letters overflowing
{ } add-letters ! "z"

add_letters({'a', 'b', 'c'}) = 'f'
add_letters({'a', 'b'}) = 'c'
add_letters({'z'}) = 'z'
add_letters({'z', 'a'}) = 'a'
add_letters({'y', 'c', 'b'}) = 'd' // notice the letters overflowing
add_letters({}) = 'z'

addLetters({'a', 'b', 'c'}) = 'f'
addLetters({'a', 'b'}) = 'c'
addLetters({'z'}) = 'z'
addLetters({'z', 'a'}) = 'a'
addLetters({'y', 'c', 'b'}) = 'd' -- notice the letters overflowing
addLetters({}) = 'z'

addLetters(@['a', 'b', 'c']) = 'f'
addLetters(@['a', 'b']) = 'c'
addLetters(@['z']) = 'z'
addLetters(@['z', 'a']) = 'a'
addLetters(@['y', 'c', 'b']) = 'd' # notice the letters overflowing
addLetters(@[]) = 'z'

AddLetters(@('a', 'b', 'c')) = 'f'
AddLetters(@('a', 'b')) = 'c'
AddLetters(@('z')) = 'z'
AddLetters(@('z', 'a')) = 'a'
AddLetters(@('y', 'c', 'b')) = 'd' # notice the letters overflowing
AddLetters(@()) = 'z'

add_letters(vec!['a', 'b', 'c']) = 'f'
add_letters(vec!['a', 'b']) = 'c'
add_letters(vec!['z']) = 'z'
add_letters(vec!['z', 'a']) = 'a'
add_letters(vec!['y', 'c', 'b']) = 'd' // notice the letters overflowing
add_letters(vec![]) = 'z'

AddLetters(new char[] {'a', 'b', 'c'}) = 'f'
AddLetters(new char[] {'a', 'b'}) = 'c'
AddLetters(new char[] {'z'}) = 'z'
AddLetters(new char[] {'z', 'a'}) = 'a'
AddLetters(new char[] {'y', 'c', 'b'}) = 'd' // notice the letters overflowing
AddLetters(new char[] {}) = 'z'

AddLetters(New Char() {"a"C, "b"C, "c"C}) = "f"C
AddLetters(New Char() {"a"C, "b"C}) = "c"C
AddLetters(New Char() {"z"C}) = "z"C
AddLetters(New Char() {"z"C, "a"C}) = "a"C
AddLetters(New Char() {"y"C, "c"C, "b"C}) = "d"C ' notice the letters overflowing
AddLetters(New Char() {}) = "z"C

AddLetters([]rune{'a', 'b', 'c'}) = 'f'
AddLetters([]rune{'a', 'b'}) = 'c'
AddLetters([]rune{'z'}) = 'z'
AddLetters([]rune{'z', 'a'}) = 'a'
AddLetters([]rune{'y', 'c', 'b'}) = 'd' // notice the letters overflowing
AddLetters([]rune{}) = 'z'

add_letters(['a', 'b', 'c']) = 'f'
add_letters(['a', 'b']) = 'c'
add_letters(['z']) = 'z'
add_letters(['z', 'a']) = 'a' # note single quotes, we work with Chars
add_letters(['y', 'c', 'b']) = 'd' # notice the letters overflowing
add_letters([] of Char) = 'z'

add_letters(["a", "b", "c"]) = "f"
add_letters(["a", "b"]) = "c"
add_letters(["z"]) = "z"
add_letters(["z", "a"]) = "a"
add_letters(["y", "c", "b"]) = "d" # notice the letters overflowing
add_letters([]) = "z"

addLetters(["a", "b", "c"]) = "f"
addLetters(["a", "b"]) = "c"
addLetters(["z"]) = "z"
addLetters(["z", "a"]) = "a"
addLetters(["y", "c", "b"]) = "d" // notice the letters overflowing
addLetters([]) = "z"

add_letters([a, b, c]) = f
add_letters([a, b]) = c
add_letters([z]) = z
add_letters([z, a]) = a
add_letters([y, c, b]) = d % notice the letters overflowing
add_letters([]) = z

addLetters(['a', 'b', 'c']) = 'f'
addLetters(['a', 'b']) = 'c'
addLetters(['z']) = 'z'
addLetters(['z', 'a']) = 'a'
addLetters(['y', 'c', 'b']) = 'd' // notice the letters overflowing
addLetters(<String>[]) = 'z'

addLetters([|"a", "b", "c"|]) = "f"
addLetters([|"a", "b"|]) = "c"
addLetters([|"z"|]) = "z"
addLetters([|"z", "a"|]) = "a"
addLetters([|"y", "c", "b"|]) = "d" /* notice the letters overflowing */
addLetters([||]) = "z"

addletters('a', 'b', 'c') = 'f'
addletters('a', 'b') = 'c'
addletters('z') = 'z'
addletters('z', 'a') = 'a' # note single quotes, we work with Chars
addletters('y', 'c', 'b') = 'd' # notice the letters overflowing
addletters() = 'z'

addLetters ['a', 'b', 'c'] = 'f'
addLetters ['a', 'b'] = 'c'
addLetters ['z'] = 'z'
addLetters ['z', 'a'] = 'a'
addLetters ['y', 'c', 'b'] = 'd' -- notice the letters overflowing
addLetters [] = 'z'

addLetters ['a', 'b', 'c'] = 'f'
addLetters ['a', 'b'] = 'c'
addLetters ['z'] = 'z'
addLetters ['z', 'a'] = 'a'
addLetters ['y', 'c', 'b'] = 'd' -- notice the letters overflowing
addLetters [] = 'z'

addLetters ['a', 'b', 'c'] = 'f'
addLetters ['a', 'b'] = 'c'
addLetters ['z'] = 'z'
addLetters ['z', 'a'] = 'a'
addLetters ['y', 'c', 'b'] = 'd' -- notice the letters overflowing
addLetters [] = 'z'

add_letters(3, {'a', 'b', 'c'}) == 'f'
add_letters(2, {'a', 'b'})      == 'c'
add_letters(1, {'z'})           == 'z'
add_letters(2, {'z', 'a'})      == 'a'
add_letters(3, {'y', 'c', 'b'}) == 'd' // notice letters overflowing
add_letters(0, {})              == 'z'

addLetters("a", "b", "c") = "f"
addLetters("a", "b") = "c"
addLetters("z") = "z"
addLetters("z", "a") = "a"
addLetters("y", "c", "b") = "d" // notice the letters overflowing
addLetters() = "z"

addLetters(listOf("a", "b", "c")) = "f"
addLetters(listOf("a", "b")) = "c"
addLetters(listOf("z")) = "z"
addLetters(listOf("z", "a")) = "a"
addLetters(listOf("y", "c", "b")) = "d" // notice the letters overflowing
addLetters(listOf()) = "z"

addLetters(List('a', 'b', 'c')) = 'f'
addLetters(List('a', 'b')) = 'c'
addLetters(List('z')) = 'z'
addLetters(List('z', 'a')) = 'a'
addLetters(List('y', 'c', 'b')) = 'd' // notice the letters overflowing
addLetters(List()) = 'z'

addLetters(["a", "b", "c"]) = "f"
addLetters(["a", "b"]) = "c"
addLetters(["z"]) = "z"
addLetters(["z", "a"]) = "a"
addLetters(["y", "c", "b"]) = "d" // notice the letters overflowing
addLetters([]) = "z"

addLetters(['a', 'b', 'c']) = 'f'
addLetters(['a', 'b']) = 'c'
addLetters(['z']) = 'z'
addLetters(['z', 'a']) = 'a'
addLetters(['y', 'c', 'b']) = 'd' // notice the letters overflowing
addLetters([]) = 'z'

addLetters({'a', 'b', 'c'}, 3) = 'f'
addLetters({'a', 'b'}, 2) = 'c'
addLetters({'z'}, 1) = 'z'
addLetters({'z', 'a'}, 2) = 'a'
addLetters({'y', 'c', 'b'}, 3) = 'd' // notice the letters overflowing
addLetters({}, 0) = 'z'

table(letter: ["a", "b", "c"]) = "f"
table(letter: ["a", "b"]) = "c"
table(letter: ["z"]) = "z"
table(letter: ["z", "a"]) = "a"
table(letter: ["y", "c", "b"]) = "d" -- notice the letters overflowing
table(letter: []) = "z"

addLetters(["a", "b", "c"]) = "f"
addLetters(["a", "b"]) = "c"
addLetters(["z"]) = "z"
addLetters(["z", "a"]) = "a"
addLetters(["y", "c", "b"]) = "d" // notice the letters overflowing
addLetters([]) = "z"

run_shell(args: ['abc']) = "f"
run_shell(args: ['ab']) = "c"
run_shell(args: ['z']) = "z"
run_shell(args: ['za']) = "a"
run_shell(args: ['ycb']) = "d" # notice the letters overflowing
run_shell(args: ['']) = "z"

(add-letters '(#\a #\b #\c)) ; #\f
(add-letters '(#\z)) ; #\z
(add-letters '(#\a #\b)) ; #\c
(add-letters '(#\c)) ; #\c
(add-letters '(#\z #\a)) ; #\a
(add-letters '(#\y #\c #\b)) ; #\d ; notice the letters overflowing
(add-letters '()) ; #\z

(add-letters [\a \b \c]) ;; \f
(add-letters [\z]) ;; \z
(add-letters [\a \b]) ;; \c
(add-letters [\c]) ;; \c
(add-letters [\z \a]) ;; \a
(add-letters [\y \c \b]) ;; \d ;; notice the letters overflowing
(add-letters []) ;; \z

runBF('abc\0') == 'f'
runBF('ab\0') == 'c'
runBF('z\0') == 'z'
runBF('za\0') == 'a'
runBF('ycb\0') == 'd' // notice the letters overflowing
runBF('\0') == 'z'

addLetters(['a', 'b', 'c'] = 'f'
addLetters(['a', 'b']) = 'c'
addLetters(['z']) = 'z'
addLetters(['z', 'a']) = 'a'
addLetters(['y', 'c', 'b']) = 'd' // notice the letters overflowing
addLetters([' ']) = 'z'

addLetters(["a", "b", "c"]) = "f"
addLetters(["a", "b"]) = "c"
addLetters(["z"]) = "z"
addLetters(["z", "a"]) = "a"
addLetters(["y", "c", "b"]) = "d" // notice the letters overflowing
addLetters([]) = "z"

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