LeetCode Math Problem Solving

//C++
class Solution {
public:
    int differenceOfSum(vector<int>& nums) {
        int elementSum=0;
        int digitSum = 0;
        for(auto num: nums){
            elementSum += num;
            while(num > 0){
                int lastDigit = num %10;    //getting the last digit
                digitSum += lastDigit;      // addding it to digit sum
                num /=10;                   // remove the last digit 
            }
        }
        return abs(elementSum-digitSum);          // returning the absolute value 
    }
};
//java
class Solution {
    public int differenceOfSum(int[] nums) {
        int arraySum=0, digitSum=0;
        for(int num: nums){
            arraySum +=num;        // adding num to arraySum in each iteration
            while(num > 0){
                digitSum += num%10;  // adding lastDigit to digitSum
                num /=10;            // deleting lastDigit from num
            }
        }
        return Math.abs(arraySum-digitSum);     // returning 'abs' val
    }
}
// Time complexity -- O(N)