66. Plus One

Description

Given a non-negative number represented as an array of digits, plus one to the number.

The digits are stored such that the most significant digit is at the head of the list.

Example 1:

Input: [1,2,3]
Output: [1,2,4]

Example 2:

Input: [9,9,9]
Output: [1,0,0,0]

Constraints:

• 1 <= digits.length <= 100.
• 0 <= digits[i] <= 9.

Solutions

I Math

Complexity:

• Time complexity: \(O(n)\).
• Space complexity: \(O(1)\).

func plusOne(digit []int) []int {
    length := len(digit)
    if length == 0 {
        return digit
    }

    for i := length - 1; i >= 0; i-- {
        if digit[i] < 9 {
            digit[i] += 1
            return digit
        }
        digit[i] = 0
    }
    digit = append([]int{1}, digit...)
    return digit
}