Add design add and search words data structure solution

Author: hyunjung-choi

design-add-and-search-words-data-structure/hyunjung-choi.kt

@@ -0,0 +1,46 @@
+class WordDictionary() {
+
+    class TrieNode {
+        val children = mutableMapOf<Char, TrieNode>()
+        var isEndOfWord = false
+    }
+
+    private val root = TrieNode()
+
+    fun addWord(word: String) {
+        var current = root
+
+        for (char in word) {
+            if (char !in current.children) {
+                current.children[char] = TrieNode()
+            }
+            current = current.children[char]!!
+        }
+
+        current.isEndOfWord = true
+    }
+
+    fun search(word: String): Boolean {
+        return searchHelper(word, 0, root)
+    }
+
+    private fun searchHelper(word: String, index: Int, node: TrieNode): Boolean {
+        if (index == word.length) {
+            return node.isEndOfWord
+        }
+
+        val char = word[index]
+
+        return if (char == '.') {
+            for (child in node.children.values) {
+                if (searchHelper(word, index + 1, child)) {
+                    return true
+                }
+            }
+            false
+        } else {
+            val child = node.children[char] ?: return false
+            searchHelper(word, index + 1, child)
+        }
+    }
+}