Plus One
Description: A number is represented as an array of digits, most significant first. Add one and return the result in the same form.
Example 1:
Input: digits = [1,2,3]
Output: [1,2,4]
Example 2:
Input: digits = [9,9]
Output: [1,0,0]
Constraints:
1 <= digits.length <= 100
0 <= digits[i] <= 9
Ведущих нулей нет
Recommended time and space complexity
O(n) time.
Hint 1
Walk from the end of the array — that is the least significant digit.
Hint 2
If a digit is less than nine, increment and return immediately.
Hint 3
If all digits are nines, the result is one element longer.