solve design add and search words data sturcture

Author: sora0319

design-add-and-search-words-data-structure/sora0319.java

@@ -0,0 +1,54 @@
+class WordDictionary {
+    private static class TrieNode {
+        boolean isEnd;
+        Map<Character, TrieNode> children;
+
+        TrieNode() {
+            this.isEnd = false;
+            this.children = new HashMap<>();
+        }
+    }
+
+    private final TrieNode root;
+
+    public WordDictionary() {
+        root = new TrieNode();
+    }
+
+    public void addWord(String word) {
+        TrieNode node = root;
+        for (char ch : word.toCharArray()) {
+            node.children.putIfAbsent(ch, new TrieNode());
+            node = node.children.get(ch);
+        }
+        node.isEnd = true;
+    }
+
+    public boolean search(String word) {
+        return dfs(root, word, 0);
+    }
+
+    private boolean dfs(TrieNode node, String word, int index) {
+        if (index == word.length()) {
+            return node.isEnd;
+        }
+
+        char ch = word.charAt(index);
+        if (ch == '.') {
+            for (TrieNode child : node.children.values()) {
+                if (dfs(child, word, index + 1)) {
+                    return true;
+                }
+            }
+            return false;
+        }
+
+        TrieNode next = node.children.get(ch);
+        if (next == null) {
+            return false;
+        }
+
+        return dfs(next, word, index + 1);
+    }
+}
+