Leetcode 17 problem

leetcode_17_phone_combination.rb

Leetcode : 17 Letter combination of phone number

# @param {String} digits
# @return {String[]}
def letter_combinations(digits)
    return [] if digits.length == 0
    hash_phone = {
        '2': ['a', 'b', 'c'],
        '3': ['d', 'e', 'f'],
        '4': ['g', 'h', 'i'],
        '5': ['j', 'k', 'l'],
        '6': ['m', 'n', 'o'],
        '7': ['p', 'q', 'r', 's'],
        '8': ['t', 'u', 'v'],
        '9': ['w', 'x', 'y', 'z']
    }
    # Next line: split and replace digits by its respective array
    rep_str_a = digits.split("").map {|d| hash_phone[:"#{d}"]}
    it_arr = rep_str_a[0]
    # Next if only one digit return single array
    return it_arr if rep_str_a.length == 1
    # Iterate and get product of each
    (1..rep_str_a.length - 1).each do |ind|
      it_arr = it_arr.product(rep_str_a[ind])
    end
    it_arr.map{|x| x.join('')}
    # rep_str_a.combination(digits.length).to_a
end

#puts letter_combinations('23')