1414 * Some resources:
1515 * <a href="https://en.wikipedia.org/wiki/Trie">Trie Data Structure</a>
1616 * <a href="https://www.topcoder.com/community/data-science/data-science-tutorials/using-tries">More about Tries</a>
17+ * <a href="https://www.youtube.com/watch?v=zIjfhVPRZCg">Video explanation from Gayle McDowell</a>
1718 *
1819 * @author rampatra
1920 * @since 9/22/15
2021 */
2122public class Trie <E > {
2223
23- TrieNode <E > root ;
24+ private class TrieNode <T > {
25+ HashMap <T , TrieNode <T >> children ;
26+ boolean isCompleteWord ; // to mark a complete word in the tri data structure
27+ 28+ TrieNode (HashMap <T , TrieNode <T >> children ) {
29+ this .children = children ;
30+ }
31+ }
32+ 33+ private TrieNode <Character > root ;
2434
2535 Trie () {
26- root = new TrieNode <>(null , new HashMap <>());
36+ root = new TrieNode <>(new HashMap <>());
2737 }
2838
2939 /**
30- * Inserts {@param data} in trie.
40+ * Inserts {@code data} in trie.
3141 *
3242 * @param data
3343 */
3444 public void insert (E data ) {
3545
3646 int i = 0 ;
3747 String str = data .toString ();
38- TrieNode <E > curr = root ;
48+ TrieNode <Character > curr = root ;
3949
4050 while (i < str .length ()) {
41- if (curr .children .get (str .substring ( i , i + 1 )) != null ) {
42- curr = curr .children .get (str .substring ( i , i + 1 ));
51+ if (curr .children .get (str .charAt ( i )) != null ) {
52+ curr = curr .children .get (str .charAt ( i ));
4353 i ++;
4454 } else {
4555 break ;
4656 }
4757 }
4858
4959 while (i < str .length ()) {
50- curr .children .put (( E ) str .substring ( i , i + 1 ), new TrieNode <>(null , new HashMap <>()));
51- curr = curr .children .get (str .substring ( i , i + 1 ));
60+ curr .children .put (str .charAt ( i ), new TrieNode <>(new HashMap <>()));
61+ curr = curr .children .get (str .charAt ( i ));
5262 i ++;
5363 }
5464
55- curr .data = data ;
65+ curr .isCompleteWord = true ;
5666 }
5767
5868 /**
@@ -63,29 +73,17 @@ public void insert(E data) {
6373 */
6474 public boolean search (E data ) {
6575
66- int i = 0 ;
6776 String str = data .toString ();
68- TrieNode <E > curr = root ;
77+ TrieNode <Character > curr = root ;
6978
70- while ( i < str .length ()) {
71- if (curr .children .get (str .substring ( i , i + 1 )) == null ) {
79+ for ( int i = 0 ; i < str .length (); i ++ ) {
80+ if (curr .children .get (str .charAt ( i )) == null ) {
7281 return false ;
7382 }
74- curr = curr .children .get (str .substring (i , i + 1 ));
75- i ++;
83+ curr = curr .children .get (str .charAt (i ));
7684 }
7785
78- return curr .data != null && curr .data .equals (data );
79- }
80- 81- private class TrieNode <T > {
82- T data ; // stores the complete string (required to determine whether the string is in the trie)
83- HashMap <T , TrieNode <T >> children ;
84- 85- TrieNode (T data , HashMap <T , TrieNode <T >> children ) {
86- this .data = data ;
87- this .children = children ;
88- }
86+ return curr .isCompleteWord ;
8987 }
9088
9189 // unit testing
@@ -101,4 +99,4 @@ public static void main(String[] args) {
10199 System .out .println (trie .search ("raz" ));
102100 System .out .println (trie .search ("rampatra" ));
103101 }
104- }
102+ }
0 commit comments