744. Find Smallest Letter Greater Than Target

class Solution:
    def nextGreatestLetter(self, letters: List[str], target: str) -> str:
        # working simple solution

        # for letter in letters:
        #     if letter > target:
        #         return letter
        # return letters[0]


        # elegant solution
        indexToInsertToKeepLettersSorted = bisect.bisect(letters, target)

        # if asked to insert at the last position,
        # we should return the first char in letters as it is cyclically next
        # if indexToInsertToKeepLettersSorted >= len(letters):
        #     return letters[0]
        # else:
        #     return letters[indexToInsertToKeepLettersSorted]

        # trick to do the if-else logic above in one math operation
        return letters[indexToInsertToKeepLettersSorted % len(letters)]