@@ -40,7 +40,7 @@ public static void main(String[] args) {
 }
 
 class TrieNode{
-    private final Map<Character,TrieNode> children = new HashMap<>();
+    private final Map<Character, TrieNode> children = new HashMap<>();
 
     public boolean isEnd = false;
 
@@ -99,3 +99,64 @@ public boolean startsWith(String prefix) {
         return true;
     }
 }
+
+
+/**
+ * 使用 数组实现
+ */
+class Trie2 {
+
+
+    TrieNode2 root = new TrieNode2();
+
+    /** Initialize your data structure here. */
+    public Trie2() {
+
+    }
+
+    /** Inserts a word into the trie. */
+    public void insert(String word) {
+        TrieNode2 curr = root;
+        for (char ch : word.toCharArray()) {
+            if(curr.children[ch - 'a'] != null){
+                curr = curr.children[ch - 'a'];
+            }else{
+                curr.children[ch - 'a'] = new TrieNode2();
+            }
+        }
+        curr.isEnd = true;
+    }
+
+    /** Returns if the word is in the trie. */
+    public boolean search(String word) {
+        TrieNode2 curr = root;
+        for (char ch : word.toCharArray()) {
+            curr = curr.children[ch - 'a'];
+            if (curr == null) {
+                return false;
+            }
+        }
+        return curr.isEnd;
+    }
+
+    /** Returns if there is any word in the trie that starts with the given prefix. */
+    public boolean startsWith(String prefix) {
+        TrieNode2 curr = root;
+        for (char c : prefix.toCharArray()) {
+            curr = curr.children[c - 'a'];
+            if (curr == null) {
+                return false;
+            }
+        }
+        return true;
+    }
+}
+
+class TrieNode2{
+    /** 因为有26个字符 */
+    public TrieNode2[] children = new TrieNode2[26];
+
+    public boolean isEnd = false;
+
+
+}
@@ -0,0 +1,83 @@
+package com.leosanqing.leetcode.medium.tree;
+
+/**
+ * @Author: rtliu
+ * @Date: 2020/6/28 下午3:58
+ * @Package: com.leosanqing.leetcode.medium.tree
+ * @Description: Design a data structure that supports the following two operations:
+ *              void addWord(word) bool search(word) search(word) can search a literal word
+ *              or a regular expression string containing only letters a-z or .. A . means it can represent any one letter.
+ *      Example:
+ *          addWord("bad")
+ *          addWord("dad")
+ *          addWord("mad")
+ *          search("pad") -> false
+ *          search("bad") -> true
+ *          search(".ad") -> true
+ *          search("b..") -> true
+ * @Version: 1.0
+ */
+public class _211_addAndSearchWord_dataStructureDesign {
+
+}
+
+class WordDictionary {
+    TrieNode1 root = new TrieNode1();
+
+    /** Initialize your data structure here. */
+    public WordDictionary() {
+
+    }
+
+    /** Adds a word into the data structure. */
+    public void addWord(String word) {
+        TrieNode1 curr = root;
+        if(word != null && word.length() > 0){
+
+            for (char c : word.toCharArray()) {
+                if (curr.children[c - 'a'] == null) {
+                    curr.children[c - 'a'] = new TrieNode1();
+                }
+                curr = curr.children[c -'a'];
+
+            }
+            curr.isEnd = true;
+
+        }
+    }
+
+    /** Returns if the word is in the data structure.
+     * A word could contain the dot character '.' to represent any one letter. */
+    public boolean search(String word) {
+        return helper(word, 0 , root);
+    }
+
+
+    private boolean helper(String word, int index, TrieNode1 curr){
+        if(index >= word.length()){
+            return curr.isEnd;
+        }
+        char c = word.charAt(index);
+
+        if('.' == c){
+            for (int i = 0; i < curr.children.length; i++) {
+                // 当出现 . 的时候，递归遍历
+                if(curr.children[i] != null && helper(word, index+1, curr.children[i])){
+                    return true;
+                }
+            }
+            return false;
+        }else {
+            return (curr.children[c - 'a'] != null) && helper(word,index +1, curr.children[c - 'a']);
+        }
+    }
+}
+
+class TrieNode1 {
+    TrieNode1[] children = new TrieNode1[26];
+
+    boolean isEnd = false;
+
+}
+
+