989. Add to Array-Form of Integer

Easy

The array-form of an integer num is an array representing its digits in left to right order.

• For example, for num = 1321, the array form is [1,3,2,1].

Given num, the array-form of an integer, and an integer k, return the array-form of the integer num + k.

Example 1:

Input: num = [1,2,0,0], k = 34
Output: [1,2,3,4]
Explanation: 1200 + 34 = 1234

Example 2:

Input: num = [2,7,4], k = 181
Output: [4,5,5]
Explanation: 274 + 181 = 455

Example 3:

Input: num = [2,1,5], k = 806
Output: [1,0,2,1]
Explanation: 215 + 806 = 1021

Constraints:

• 1 <= num.length <= 10^4

• 0 <= num[i] <= 9

• num does not contain any leading zeros except for the zero itself.

• 1 <= k <= 10^4

解題

func addToArrayForm(num []int, k int) []int {
    carry := k
    
    for i:=len(num)-1; i>=0; i-- {
        num[i] += carry 
        carry = num[i]/10
        num[i] = num[i]%10
    }

    if carry != 0 {
        for carry > 0 {
            remainder := carry % 10
            carry /= 10
            num = append([]int{remainder}, num...)
        }
    }

    return num
}