Basic Search Ternary Search Tree Implementation

Author: IskandarFischer

DataStructures/Trees/TernarySearchTree.cs

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+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace DataStructures.Trees
+{
+    public class TernarySearchTree
+    {
+        public TernaryTreeNode Root { get; private set; }
+
+        public void Insert(string word)
+        {
+            if (string.IsNullOrWhiteSpace(word))
+                throw new Exception("Inputted value is empty");
+
+            if (Root == null)
+                Root = new TernaryTreeNode(null, word[0], word.Length == 1);
+
+            WordInsertion(word);
+        }
+
+        public void Insert(string[] words)
+        {
+            foreach (var word in words)
+            {
+                Insert(word);
+            }
+        }
+
+        void WordInsertion(string word)
+        {
+            int index = 0;
+            TernaryTreeNode currentNode = Root;
+
+            while (index < word.Length)
+                currentNode = ChooseNode(currentNode, word, ref index);
+        }
+
+        TernaryTreeNode ChooseNode(TernaryTreeNode currentNode, string word, ref int index)
+        {
+            //Center Branch
+            if (word[index] == currentNode.Value)
+            {
+                index++;
+
+                if (currentNode.GetMiddleChild == null)
+                    InsertInTree(currentNode.AddMiddleChild(word[index], word.Length == index + 1), word, ref index);
+                
+
+                return currentNode.GetMiddleChild;
+            }
+            //Right Branch
+            else if (word[index] > currentNode.Value)
+            {
+                if (currentNode.GetRightChild == null)
+                    InsertInTree(currentNode.AddRightChild(word[index], word.Length == index + 1), word, ref index);
+
+                return currentNode.GetRightChild;
+            }
+            //Left Branch
+            else
+            {
+                if (currentNode.GetLeftChild == null)
+                    InsertInTree(currentNode.AddLeftChild(word[index], word.Length == index + 1), word, ref index);
+
+                return currentNode.GetLeftChild;
+            }
+        }
+
+        void InsertInTree(TernaryTreeNode currentNode, string word, ref int currentIndex)
+        {
+            int length = word.Length;
+
+            currentIndex++;
+            var currNode = currentNode;
+            for (int i = currentIndex; i < length; i++)
+                currNode = currNode.AddMiddleChild(word[i], word.Length == currentIndex + 1);
+
+            currentIndex = length;
+        }
+    }
+}

DataStructures/Trees/TernaryTreeNode.cs

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+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace DataStructures.Trees
+{
+    public class TernaryTreeNode
+    {
+        public virtual TernaryTreeNode Parent { get; private set; }
+        protected virtual TernaryTreeNode[] childs { get; set; }
+
+        public virtual TernaryTreeNode GetLeftChild { get { return childs[0]; } }
+        public virtual TernaryTreeNode GetMiddleChild { get { return childs[1]; } }
+        public virtual TernaryTreeNode GetRightChild { get { return childs[2]; } }
+
+        public virtual bool FinalLetter { get; set; }
+        public virtual char Value { get; set; }
+
+        public TernaryTreeNode(TernaryTreeNode parent)
+        {
+            this.Parent = parent;
+            childs = new TernaryTreeNode[3];
+        }
+
+        public TernaryTreeNode(TernaryTreeNode parent, char value, bool isFinal)
+        {
+            this.Parent = parent;
+            this.Value = value;
+            this.FinalLetter = isFinal;
+            childs = new TernaryTreeNode[3];
+        }
+
+        public virtual TernaryTreeNode AddLeftChild(char value, bool isFinal)
+        {
+            childs[0] = new TernaryTreeNode(this, value, isFinal);
+            return childs[0];
+        }
+        public virtual TernaryTreeNode AddRightChild(char value, bool isFinal)
+        {
+            childs[2] = new TernaryTreeNode(this, value, isFinal);
+            return childs[2];
+        }
+        public virtual TernaryTreeNode AddMiddleChild(char value, bool isFinal)
+        {
+            childs[1] = new TernaryTreeNode(this, value, isFinal);
+            return childs[1];
+        }
+    }
+}

UnitTest/DataStructuresTests/TernarySearchTreeTest.cs

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+using DataStructures.Trees;
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Xunit;
+
+namespace UnitTest.DataStructuresTests
+{
+    public static class TernarySearchTreeTest
+    {
+
+        //         c
+        //       / | \
+        //      a  u  h
+        //      |  |  | \
+        //      t  t  e u
+        //     /  / |  / |
+        //    s  p  e i  s
+        [Fact]
+        public static void DoTest()
+        {
+            string[] words = new string[] { "cute", "cup", "at", "as", "he", "us", "i" };
+
+            TernarySearchTree tree = new TernarySearchTree();
+
+            tree.Insert(words);
+
+            Assert.Equal('c', tree.Root.Value);
+            Assert.Equal('h', tree.Root.GetRightChild.Value);
+            Assert.Equal('e', tree.Root.GetRightChild.GetMiddleChild.Value);
+            Assert.Equal('p', tree.Root.GetMiddleChild.GetMiddleChild.GetLeftChild.Value);
+            Assert.Equal('s', tree.Root.GetLeftChild.GetMiddleChild.GetLeftChild.Value);
+
+        }
+    }
+}