Leetcode Everyday: 1295. Find Numbers with Even Number of Digits. Easy

Functional programming:

using static System.Math;

public class Solution {
    public int FindNumbers(int[] nums) =>
        nums.Count(num => CountDigit(num) % 2 == 0);
    
    public int CountDigit(int n) => (int)Max(Log10(n), 0) + 1;
}

Imperative programming:

using static System.Math;

public class Solution {
    public int FindNumbers(int[] nums) {
        int evenCount = 0;
        foreach (var num in nums) {
            if (CountDigit(num) % 2 == 0) {
                ++evenCount;
            }  
        }
        return evenCount;
        
        int CountDigit(int num) {            
            int digit = 0;
            for (; num != 0; num /= 10) {
                ++digit;
            }
            return Max(digit, 1);
        }
    }
}

Source: https://leetcode.com/problems/find-numbers-with-even-number-of-digits/submissions/