| 4 | ) |
| 5 | |
| 6 | class Trie { |
| 7 | val root = TrieNode() |
| 8 | |
| 9 | fun insert(word: String) { |
| 10 | var node = root |
| 11 | for (c in word.toCharArray()) { |
| 12 | // For each character in the word, if it's not a child of |
| 13 | // the current node, create a new TrieNode for that |
| 14 | // character. |
| 15 | if (c !in node.children) { |
| 16 | node.children[c] = TrieNode() |
| 17 | } |
| 18 | node = node.children[c]!! |
| 19 | } |
| 20 | // Mark the last node as the end of a word. |
| 21 | node.isWord = true |
| 22 | } |
| 23 | |
| 24 | fun search(word: String): Boolean { |
| 25 | var node = root |
| 26 | for (c in word.toCharArray()) { |
| 27 | // For each character in the word, if it's not a child of |
| 28 | // the current node, the word doesn't exist in the Trie. |
| 29 | if (c !in node.children) { |
| 30 | return false |
| 31 | } |
| 32 | node = node.children[c]!! |
| 33 | } |
| 34 | // Return whether the current node is marked as the end of the word. |
| 35 | return node.isWord |
| 36 | } |
| 37 | |
| 38 | fun hasPrefix(prefix: String): Boolean { |
| 39 | var node = root |
| 40 | for (c in prefix.toCharArray()) { |
| 41 | if (c !in node.children) { |
| 42 | return false |
| 43 | } |
| 44 | node = node.children[c]!! |
| 45 | } |
| 46 | // Once we've traversed the nodes corresponding to each |
| 47 | // character in the prefix, return True. |
| 48 | return true |
| 49 | } |
| 50 | } |