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2535 - Difference Between Element Sum and Digit Sum of an Array (Easy)

https://leetcode.com/problems/difference-between-element-sum-and-digit-sum-of-an-array/

Problem Statement​

You are given a positive integer array nums.

  • The element sum is the sum of all the elements in nums.
  • The digit sum is the sum of all the digits (not necessarily distinct) that appear in nums.

Return the absolute difference between the element sum and digit sum ofnums.

Note that the absolute difference between two integers x and y is defined as |x - y|.

Example 1:

Input: nums = [1,15,6,3]
Output: 9
Explanation: 
The element sum of nums is 1 + 15 + 6 + 3 = 25.
The digit sum of nums is 1 + 1 + 5 + 6 + 3 = 16.
The absolute difference between the element sum and digit sum is |25 - 16| = 9.

Example 2:

Input: nums = [1,2,3,4]
Output: 0
Explanation:
The element sum of nums is 1 + 2 + 3 + 4 = 10.
The digit sum of nums is 1 + 2 + 3 + 4 = 10.
The absolute difference between the element sum and digit sum is |10 - 10| = 0.

Constraints:

  • 1 <= nums.length <= 2000
  • 1 <= nums[i] <= 2000

Approach 1: Straight Forward​

Written by @wingkwong
class Solution {
public:
    int f(int x) {
        int res = 0;
        while (x) {
            // get the last digit
            res += x % 10;
            // divide by 10 to remove the last digit
            x /= 10;
        }
        return res;
    }
    int differenceOfSum(vector<int>& nums) {
        int es = 0, ds = 0;
        for (auto x : nums) {
            // calculate element sum
            es += x;
            // calculate digit sum
            ds += f(x);
        }
        // return the absolute difference between the element sum and digit sum of nums.
        return abs(es - ds);
    }
};