Fix #559: Add Trie [c#] (#592)

* Implemented Trie C#

* Added check mark under Trie c#

* Fixed syntax

README.md

@@ -57,7 +57,7 @@ Community (college) maintained list of Algorithms and Data Structures implementa
 | [Binary Search Tree](https://en.wikipedia.org/wiki/Binary_search_tree) | | | [:white_check_mark:](binary_search_tree/BinarySearchTree.java) | | [:white_check_mark:](binary_search_tree/binary_search_tree.go) | | |
 | [Linked List](https://en.wikipedia.org/wiki/Linked_list) | [:white_check_mark:](linked_list/linkedList.c.c) | | [:white_check_mark:](linked_list/LinkedList.java) | [:white_check_mark:](linked_list/linked_list.py) | [:white_check_mark:](linked_list/linked_list.go) | [:white_check_mark:](linked_list/linkedList.js) | [:white_check_mark:](linked_list/LinkedList.cs) |
 | [Stack](https://en.wikipedia.org/wiki/Stack_(abstract_data_type)) | [:white_check_mark:](stack/stack.c) | | [:white_check_mark:](stack/Stack.java) | [:white_check_mark:](stack/stack.py) | [:white_check_mark:](stack/stack.go) | [:white_check_mark:](stack/stack.js) | [:white_check_mark:](stack/Stack.cs) |
-| [Trie](https://en.wikipedia.org/wiki/Trie) | | [:white_check_mark:](trie/trie.cpp) | [:white_check_mark:](trie/Trie.java) | | [:white_check_mark:](trie/trie.go) | | | |
+| [Trie](https://en.wikipedia.org/wiki/Trie) | | [:white_check_mark:](trie/trie.cpp) | [:white_check_mark:](trie/Trie.java) | | [:white_check_mark:](trie/trie.go) | | [:white_check_mark:](trie/Trie.cs) | |
 
 
 

trie/Trie.cs

@@ -0,0 +1,90 @@
+using System;
+using System.Collections.Generic;
+
+class TrieNode
+{
+    public char c;
+    public Dictionary<char, TrieNode> children;
+    public bool isWord;
+
+    public TrieNode()
+    {
+        children = new Dictionary<char, TrieNode>();
+    }
+
+    public TrieNode(char c)
+    {
+        this.c = c;
+        children = new Dictionary<char, TrieNode>();
+    }
+}
+
+public class Trie
+{
+    private TrieNode root;
+
+    public Trie()
+    {
+        root = new TrieNode();
+    }
+
+    /// <summary>
+    /// Inserts a word into the Trie
+    /// Time Complexity: O(len(word))
+    /// </summary>
+    /// <param name="word">The word to insert</param>
+    public void Insert(String word)
+    {
+        TrieNode curr = root;
+
+        foreach (char c in word)
+        {
+            if (!curr.children.ContainsKey(c))
+                curr.children[c] = new TrieNode(c);
+
+            curr = curr.children[c];
+        }
+
+        curr.isWord = true;
+    }
+
+    /// <summary>
+    /// Searches the trie for a word
+    /// Time Complexity: O(len(word))
+    /// </summary>
+    /// <param name="word">The word to search for</param>
+    /// <returns>True if the word was found, false otherwise</returns>
+    public bool Search(String word)
+    {
+        TrieNode curr = root;
+
+        foreach (char c in word)
+        {
+            if (!curr.children.ContainsKey(c))
+                return false;
+
+            curr = curr.children[c];
+        }
+
+        return curr.isWord;
+    }
+
+    public static void Main()
+    {
+        Trie dictionary = new Trie();
+        // Input keys words
+        dictionary.Insert("the");
+        dictionary.Insert("a");
+        dictionary.Insert("there");
+        dictionary.Insert("answer");
+        dictionary.Insert("any");
+        dictionary.Insert("by");
+        dictionary.Insert("bye");
+        dictionary.Insert("their");
+        // Search for different keys words
+        Console.WriteLine(dictionary.Search("the"));
+        Console.WriteLine(dictionary.Search("these"));
+        Console.WriteLine(dictionary.Search("thaw"));
+        Console.WriteLine(dictionary.Search("their"));
+    }
+}