Merge pull request neetcode-gh#660 from tahmid26/main

Add 211-Design-Add-and-Search-Words-Data-Structure.java

Author: Ahmad-A0

java/211-Design-Add-and-Search-Words-Data-Structure.java

@@ -0,0 +1,74 @@
+class WordDictionary {
+
+    Node root;
+    
+    public class Node{
+        char value;
+        boolean isWord;
+        Node[] children;
+        
+        public Node(char value) {
+            this.value = value;
+            isWord = false;
+            children = new Node[26];
+        }
+    }
+    public WordDictionary() {
+        root = new Node('\0');
+    }
+    
+    public void addWord(String word) {
+        Node curr = root;
+        
+        for (int i = 0; i < word.length(); i++) {
+            char ch = word.charAt(i);
+            
+            if (curr.children[ch - 'a'] == null)
+                curr.children[ch - 'a'] = new Node(ch);
+            
+            curr = curr.children[ch - 'a'];
+            
+        }
+          curr.isWord = true;
+    }
+    
+    
+    // TC O(m^2)
+    public boolean search(String word) {
+        Node curr = root;       // assigns the node that called the search function
+        return searchHelper(word, root);
+        
+    }
+    
+     public boolean searchHelper(String word, Node curr) {
+         
+     for (int i = 0; i < word.length(); i++) {
+            char ch = word.charAt(i);
+            
+            if(ch == '.') {
+                for(Node temp: curr.children) {
+                    if(temp != null && searchHelper(word.substring(i+1), temp)) 
+                        return true;
+                }
+                return false;
+            }
+            
+            if (curr.children[ch - 'a'] == null)
+                return false;
+            
+            curr = curr.children[ch - 'a'];
+        }
+        
+        if (curr.isWord == true)
+            return true;
+        else
+            return false;
+     }
+}
+
+/**
+ * Your WordDictionary object will be instantiated and called as such:
+ * WordDictionary obj = new WordDictionary();
+ * obj.addWord(word);
+ * boolean param_2 = obj.search(word);
+ */