Created
August 19, 2021 15:30
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| class Trie { | |
| public static void main(String[] args) { | |
| String s = "tttt"; | |
| Trie t = new Trie(); | |
| t.insert(s); | |
| t.insert("ttt"); | |
| System.out.println(t.startsWith("tt")); | |
| } | |
| class Node { | |
| Node[] children = new Node[26]; | |
| boolean isCompleted; | |
| } | |
| private Node root; | |
| public Trie() { | |
| root = new Node(); | |
| } | |
| public void insert(String s) { | |
| Node node = root; | |
| for (int i = 0; i < s.length(); i++) { | |
| char c = s.charAt(i); | |
| if (node.children[c - 'a'] == null) { | |
| node.children[c - 'a'] = new Node(); | |
| } | |
| node = node.children[c - 'a']; // moves pointer down. | |
| } | |
| node.isCompleted = true; | |
| } | |
| public boolean search(String word) { | |
| Node node = searchNode(word); | |
| if (node == null) { | |
| return false; | |
| } | |
| return node.isCompleted; | |
| } | |
| public boolean startsWith(String prefix) { | |
| Node node = searchNode(prefix); | |
| if (node == null) { | |
| return false; | |
| } | |
| return true; | |
| } | |
| public Node searchNode(String s) { | |
| Node node = root; | |
| for (int i = 0; i < s.length(); i++) { | |
| char c = s.charAt(i); | |
| if (node.children[c - 'a'] == null) { | |
| return null; | |
| } else { | |
| node = node.children[c - 'a']; | |
| } | |
| } | |
| return node; | |
| } | |
| } |
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