Element Spellable Recursion Challenge

Given a word and an array of element symbols, determine whether the word can be spelled by concatenating symbols from the list. Matching is case-insensitive, but the returned symbols must preserve the capitalization from the symbols array. Each symbol may be used more than once.

Function Signature

elementSpellable(text, symbols)

Parameters

• text — a string representing the word to spell.
• symbols — an array of strings representing available element symbols (e.g. ['Be', 'Ga', 'N']).

Output

Return an array of symbols (with original capitalization) that spell the word, or null if the word cannot be spelled. An empty string should return [].

Constraints

• The function must use recursion.
• Matching is case-insensitive.
• Returned symbols must preserve capitalization from the input array.
• The function should accept exactly two arguments.

Examples

elementSpellable('began', ['Be', 'Ga', 'N'])   → ['Be', 'Ga', 'N']
elementSpellable('feline', ['Fe', 'Li', 'Ne'])  → ['Fe', 'Li', 'Ne']
elementSpellable('BeGaN', ['Be', 'Ga', 'N'])    → ['Be', 'Ga', 'N']
elementSpellable('interesting', ['I', 'N', 'Te']) → null
elementSpellable('', ['H', 'He'])               → []
elementSpellable('began', [])                   → null

Edge Cases

• An empty string is always spellable and returns [].
• An empty symbols array with a non-empty word returns null.
• Some words require backtracking when a greedy match leads to a dead end.