feat(DetectPangram): add solution.

CodeWarsChallenges/CodeWarsChallenges/Strings/6kyu/Detect Pangram/DetectPangram.cs

@@ -0,0 +1,60 @@
+namespace CodeWarsChallenges.Strings._6kyu.Detect_Pangram;
+
+public static class DetectPangram
+{
+    private static readonly HashSet<int> ASCIIAlphabet = new()
+    {
+        65,
+        66,
+        67,
+        68,
+        69,
+        70,
+        71,
+        72,
+        73,
+        74,
+        75,
+        76,
+        77,
+        78,
+        79,
+        80,
+        81,
+        82,
+        83,
+        84,
+        85,
+        86,
+        87,
+        88,
+        89,
+        90
+    };
+
+
+    public static bool IsPangram(string str)
+    {
+        var countAlphabet = ASCIIAlphabet.Count;
+        var hashSet = new HashSet<int>();
+        var stringUpper = str.ToUpper();
+        var count = 0;
+
+        for (var i = 0; i < stringUpper.Length; i++)
+        {
+            if (count == countAlphabet) 
+                return true;
+
+            if (!ASCIIAlphabet.Contains((int)stringUpper[i])) 
+                continue;
+
+            if (hashSet.Contains((int) stringUpper[i]))
+                continue;
+
+            hashSet.Add(stringUpper[i]);
+            count++;
+        }
+
+        return count == countAlphabet;
+    }
+}