add solution of design-add-and-search-words-data-structure

Author: jinhyungrhee

design-add-and-search-words-data-structure/jinhyungrhee.java

@@ -0,0 +1,56 @@
+class TrieNode {
+    boolean word;
+    TrieNode[] children;
+
+    TrieNode() {
+        this.word = false;
+        this.children = new TrieNode[27];
+    }
+}
+
+class WordDictionary {
+    TrieNode root;
+    public WordDictionary() {
+        this.root = new TrieNode();
+    }
+
+    public void addWord(String word) {
+
+        TrieNode curr = root;
+        for (char c : word.toCharArray()) {
+            if (curr.children[c - 'a'] == null) {
+                curr.children[c - 'a'] = new TrieNode();
+            }
+            curr = curr.children[c - 'a'];
+        }
+        curr.word = true;
+    }
+
+    public boolean search(String word) {
+        return dfs(word, 0, root);
+    }
+
+    public boolean dfs(String word, int index, TrieNode node) {
+
+        if (index == word.length()) {
+            return node.word;
+        }
+
+        char c = word.charAt(index);
+
+        if (c == '.') {
+            for (TrieNode child : node.children) {
+                if (child != null && dfs(word, index + 1, child)) {
+                    return true;
+                }
+            }
+            return false;
+
+        } else {
+
+            TrieNode next = node.children[c - 'a'];
+            return next != null && dfs(word, index + 1, next);
+
+        }
+    }
+}