Given an array of strings made only from lowercase letters, return a list of all characters that show up in all strings within the list (including duplicates). For example, if a character occurs 3 times in all strings but not 4 times, you need to include that character three times in the final answer:
Input:["cool","lock","cook"] Output:["c","o"]
Hints
Often when solving code challenges, specific words or phrases used provide clues for how best to approach the problem. For this challenge we see the word duplicates highlighted. Can you think of the an algorithm or data structure that addresses the common scenario of duplicates? How could this model be used to help us find common characters?