Create a function parse which accepts exactly one argument string / $string / s / strrep ( or similar, depending on the language )
which is a string representation of a linked list. Your function must return the corresponding linked list, constructed from instances of
the Node class/struct/type. The string representation of a list has the following format: the value of the node, followed by a whitespace,
an arrow and another whitespace (" -> "), followed by the rest of the linked list. Each string representation of a linked list will end in
"null" / "NULL" / "nil" / "nullptr" / "null()" depending on the language you are undertaking this Kata in. For example, given the
following string representation of a linked list:
new Node(1, new Node(2, new Node(3)))
Note that due to the way the constructor for Node is defined, if a second argument is not provided, the next / $next / Next field is
automatically set to null / NULL / nil / nullptr ( or equivalent in your language ). That means your function could also return the
following ( if it helps you better visualise what is actually going on ):
new Node(1, new Node(2, new Node(3, null)))
Another example: given the following string input:
"0 -> 1 -> 4 -> 9 -> 16 -> null"
... your function should return:
new Node(0, new Node(1, new Node(4, new Node(9, new Node(16)))))
If the input string is just "null" / "NULL" / "nil" / "nullptr" / "null()", return null / NULL / nil / nullptr /
null() / [] ( or equivalent ).
For the simplicity of this Kata, the values of the nodes in the string representation will always ever be non-negative integers, so the
following would not occur: "Hello World -> Goodbye World -> 123 -> null" / "Hello World -> Goodbye World -> 123 -> NULL" /
"Hello World -> Goodbye World -> 123 -> nil" / "Hello World -> Goodbye World -> 123 -> nullptr" ( depending on the language ). This also
means that the values of each Node must also be non-negative integers so keep that in mind when you are parsing the list from the
string.