Add 208_Implement_Trie_(Prefix Tree).java

Author: Sean Prashad

Custom Data Structures/208_Implement_Trie_(Prefix Tree).java

@@ -0,0 +1,88 @@
+class TrieNode {
+ private Map<Character, TrieNode> children;
+ private boolean isWord;
+
+ public TrieNode() {
+ children = new HashMap<>();
+ isWord = false;
+ }
+
+ public boolean isWord() {
+ return isWord;
+ }
+
+ public void isFullWord() {
+ isWord = true;
+ }
+
+ public void putCharIfAbsent(char c) {
+ children.putIfAbsent(c, new TrieNode());
+ }
+
+ public TrieNode getChild(char c) {
+ return children.get(c);
+ }
+}
+
+class Trie {
+ private TrieNode root;
+
+ /** Initialize your data structure here. */
+ public Trie() {
+ root = new TrieNode();
+ }
+
+ /** Inserts a word into the trie. */
+ public void insert(String word) {
+ if (word == null) {
+ return;
+ }
+
+ TrieNode curr = root;
+ for (char c : word.toCharArray()) {
+ curr.putCharIfAbsent(c);
+ curr = curr.getChild(c);
+ }
+
+ curr.isFullWord();
+ }
+
+ /** Returns if the word is in the trie. */
+ public boolean search(String word) {
+ if (word == null) {
+ return false;
+ }
+
+ TrieNode curr = root;
+
+ for (char c : word.toCharArray()) {
+ curr = curr.getChild(c);
+
+ if (curr == null) {
+ return false;
+ }
+ }
+
+ return curr.isWord();
+ }
+
+ /**
+ * Returns if there is any word in the trie that starts with the given prefix.
+ */
+ public boolean startsWith(String prefix) {
+ if (prefix == null) {
+ return false;
+ }
+
+ TrieNode curr = root;
+
+ for (char c : prefix.toCharArray()) {
+ curr = curr.getChild(c);
+ if (curr == null) {
+ return false;
+ }
+ }
+
+ return true;
+ }
+}