Insert And Search Words With Wildcards

Author: marttp

kotlin/Tries/InsertAndSearchWordsWithWildcards.kt

@@ -0,0 +1,50 @@
+/*
+    Definition of a TrieNode:
+
+    data class TrieNode(
+        var isWord: Boolean = false,
+        val children: HashMap<Char, TrieNode> = hashMapOf()
+    )
+*/
+
+class InsertAndSearchWordsWithWildcards {
+    private val root = TrieNode()
+
+    fun insert(word: String) {
+        var node = root
+        for (c in word) {
+            if (c !in node.children) {
+                node.children[c] = TrieNode()
+            }
+            node = node.children[c]!!
+        }
+        node.isWord = true
+    }
+
+    fun search(word: String): Boolean {
+        // Start searching from the root of the trie.
+        return searchHelper(0, word, root)
+    }
+
+    fun searchHelper(wordIndex: Int, word: String, node: TrieNode): Boolean {
+        var node = node
+        for (i in wordIndex until word.length) {
+            val c = word[i]
+            if (c == '.') {
+                for (child in node.children.values) {
+                    // If a match is found, return true.
+                    if (searchHelper(i + 1, word, child)) {
+                        return true
+                    }
+                }
+            } else if (c in node.children) {
+                node = node.children[c]!!
+            } else {
+                return false
+            }
+            // After processing the last character, return true if we've
+            // reached the end of a word.
+        }
+        return node.isWord
+    }
+}