second commit. Submission of weekly challenges set mvdoyle#2.

Author: GrantHillDev

ChallengesWithTestsMark8.Tests/bin/Debug/netcoreapp3.1/ChallengesWithTestsMark8.Tests.dll

@@ -1,58 +1,156 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 
 namespace ChallengesWithTestsMark8
 {
     public class ChallengesSet02
     {
         public bool CharacterIsALetter(char c)
         {
-            throw new NotImplementedException();
+            return char.IsLetter(c);
         }
 
         public bool CountOfElementsIsEven(string[] vals)
         {
-            throw new NotImplementedException();
+            if (vals.Length % 2 ==0)
+            {
+                return true;
+            }
+            else
+            {
+                return false;
+            }
+     
         }
 
         public bool IsNumberEven(int number)
         {
-            throw new NotImplementedException();
+            if (number % 2 == 0)
+            {
+                return true;
+            }
+            else
+            {
+                return false;
+            }
         }
 
         public bool IsNumberOdd(int num)
         {
-            throw new NotImplementedException();
+            if (num % 2 != 0)
+            {
+                return true;
+            }
+            else
+            {
+                return false;
+            }
         }
 
         public double SumOfMinAndMax(IEnumerable<double> numbers)
         {
-            throw new NotImplementedException();
+            if (numbers == null)
+            {
+                return 0;
+            }
+            if (numbers.Count() == 0)
+            {
+                return 0;
+            }
+            return numbers.Min() + numbers.Max();
+            // return numbers?.Any() ?? false ? numbers.Min() + numbers.Max() : new double { };
         }
 
         public int GetLengthOfShortestString(string str1, string str2)
         {
-            throw new NotImplementedException();
+            if (str1.Length < str2.Length)
+            {
+                return str1.Length;
+            }
+            else if (str1 == str2)
+            {
+                return 0;
+            }
+            else
+            {
+                return str2.Length;
+            }
+            // return new int {str1.Length, str2.Length}.Min();
         }
 
         public int Sum(int[] numbers)
         {
-            throw new NotImplementedException();
+            if (numbers == null)
+            {
+                return 0;
+            }
+          
+            int sum = 0;
+
+            for (int i = 0; i < numbers.Length; i++)
+            {
+                sum += numbers[i];
+            }
+
+            return sum;
+            // return numbers?.Sum() ?? 0;
         }
 
         public int SumEvens(int[] numbers)
         {
-            throw new NotImplementedException();
+            if (numbers == null)
+            {
+                return 0;
+            }
+
+            int sumEven = 0;
+
+            for (int i = 0; i < numbers.Length; i++)
+            {
+                if (numbers[i] % 2 == 0)
+                {
+                    sumEven += numbers[i];
+                }
+            }
+            return sumEven;
+            // return numbers?.Sum(x => x % 2 == 0 ? x : 0) ?? 0;
         }
 
         public bool IsSumOdd(List<int> numbers)
         {
-            throw new NotImplementedException();
+            if (numbers == null)
+            {
+                return false;
+            }
+            return numbers.Sum() % 2 != 0;
         }
 
         public long CountOfPositiveOddsBelowNumber(long number)
         {
-            throw new NotImplementedException();
+            //var count = 0;
+
+            //    if (number == 1 || number <= 0)
+            //    {
+            //        return 0;
+            //    }
+            //    for (long i = number; i > 0; i--)
+            //    {
+            //        if(i % 2 ==0)
+            //        {
+            //            count++;
+            //        }
+            //    }
+            //    return count;
+            //}
+            if (number <= 0)
+            {
+                return 0;
+            }
+            else
+            {
+                return number / 2;
+            }
         }
     }
 }