2180. Count Integers With Even Digit Sum

Given a positive integer num, return the number of positive integers less than or equal to num whose digit sums are even. The digit sum of a positive integer is the sum of all its digits. Example 1: Input: num = 4 Output: 2 Explanation: The only integers less than or equal to 4 whose digit sums are even are 2 and 4. Example 2: Input: num = 30 Output: 14 Explanation: The 14 integers less tha