Implement ternary search delete and containsKey

Author: cschen1205

Algorithms/DataStructures/SearchTries/TernarySearchTries.cs

@@ -88,14 +88,28 @@ private Node Get(Node x, string key, int d)
 
         public int Count => N;
         public bool IsEmpty => N == 0;
+
         public void Delete(string key)
         {
-            throw new System.NotImplementedException();
+            Node x = Get(root, key, 0);
+            if (x != null)
+            {
+                if (!ObjectUtil.IsNullOrDefault(x.value))
+                {
+                    N--;
+                }
+                x.value = default(T);
+            }
         }
 
         public bool ContainsKey(string key)
         {
-            throw new System.NotImplementedException();
+            Node x = Get(root, key, 0);
+            if(x !=null)
+            {
+                return !ObjectUtil.IsNullOrDefault(x.value);
+            }
+            return false;
         }
 
         public IEnumerable<string> Keys { get; }

AlgorithmsUnitTest/DataStrutures/SearchTries/TernarySearchTriesUnitTest.cs

@@ -27,13 +27,14 @@ public void TestSearchTries()
             Assert.Equal(2, map.Count);
 
 
-            /*
+
             map.Delete("two");
             Assert.Equal(1, map.Count);
             Assert.True(map.ContainsKey("one"));
             Assert.False(map.ContainsKey("two"));
             Assert.False(map.IsEmpty);
 
+            /*
 
             foreach(var key in map.Keys)
             {