Math Number tricks

88. Plus One

You are given a non-negative integer written as an array digits. Each element is one decimal digit, and the most significant digit comes first, so [4, 0, 7] is the number 407.

Add one to the number and return the result as an array in the same form: one digit per element, most significant digit first, with no leading zeros.

Example 1

Input: digits = [6, 0, 9, 9]

Output: [6,1,0,0]

Explanation: The number is 6,099, and 6,099 + 1 = 6,100. The two 9s at the end become 0s, the 0 before them becomes a 1, and the 6 stays as it is.

Example 2

Input: digits = [9, 9, 9]

Output: [1,0,0,0]

Explanation: 999 + 1 = 1,000. The answer has one more digit than the input.

Example 3

Input: digits = [0]

Output: [1]

Explanation: The number 0 is written as [0], the only input that may start with a 0. Adding one gives 1.

Check your understanding

Work out the answer for this input before you write any code.

digits = [2, 9, 9]

Constraints

1 ≤ digits.length ≤ 10⁵
0 ≤ digits[i] ≤ 9
digits has no leading zeros, except for the number 0 itself, which is [0].

Clarifying questions

What you would ask an interviewer before writing any code.