# You are given a large integer represented as an integer array digits, where
# each digits[i] is the ith digit of the integer. The digits are ordered from
# most significant to least significant in left-to-right order. The large
# integer does not contain any leading 0's.
#
# Increment the large integer by one and return the resulting array of digits.

# increment by one the last index of the array.
# iterate backwards, from the last index until index 0,
# if the index as a value of 10, set it to 0;
#   if this is the index 0, insert the value 1 at index 1,
#   otherwise increment the previous index by 1
#   (we are running backwards in the array)


def plusOne(digits: list[int]) -> list[int]:
    digits[-1] += 1
    for n_digit in range(len(digits) - 1, -1, -1):
        if digits[n_digit] == 10:
            digits[n_digit] = 0
            if n_digit == 0:
                digits.insert(0, 1)
            else:
                digits[n_digit - 1] += 1
    return digits