33// #Medium #Top_100_Liked_Questions #Top_Interview_Questions #String #Hash_Table #Design #Trie
44// #Level_2_Day_16_Design #Udemy_Trie_and_Heap
55// #Big_O_Time_O(word.length())_or_O(prefix.length())_Space_O(N)
6- // #2022_06_28_Time_34_ms_ (99.90%)_Space_51_MB_(94.92 %)
6+ // #2024_11_15_Time_30_ms_ (99.78%)_Space_55.1_MB_(72.51 %)
77
88@ SuppressWarnings ("java:S1104" )
99public class Trie {
10- private final TrieNode root ;
11- private boolean startWith ;
12-
13- private static class TrieNode {
14- // Initialize your data structure here.
15- public TrieNode [] children ;
16- public boolean isWord ;
10+ boolean ans =false ;
11+ TrieNode [] trees =new TrieNode [26 ];
12+ public Trie () {
1713
18- public TrieNode () {
19- children = new TrieNode [26 ];
20- }
2114 }
2215
23- public Trie () {
24- root = new TrieNode ();
16+ TrieNode mapWordToTree (TrieNode t , String word , int i ){
17+ char m =word .charAt (i );
18+ boolean found =false ;
19+ TrieNode a =t .nexts [m -'a' ];
20+ if (a !=null ){
21+ if (i !=word .length ()-1 ){
22+ mapWordToTree (a ,word ,i +1 );
23+ found =true ;
24+
25+ }else {
26+ a .end =true ;
27+ found =true ;
28+ }
29+ }
30+ if (!found ){
31+ TrieNode prev =t ;
32+ for (int j =i ;j <word .length ();j ++){
33+ TrieNode temp =new TrieNode (word .charAt (j ));
34+ prev .nexts [word .charAt (j )-'a' ]=temp ;
35+ prev =temp ;
36+ }
37+ prev .end =true ;
38+ }
39+ return t ;
2540 }
2641
27- // Inserts a word into the trie.
2842 public void insert (String word ) {
29- insert (word , root , 0 );
43+ char a =word .charAt (0 );
44+ if (trees [a -'a' ]==null ){
45+ TrieNode t =new TrieNode (a );
46+ trees [a -'a' ]=t ;
47+ if (1 ==word .length ()){
48+ trees [a -'a' ].end =true ;
49+ return ;
50+ }
51+ trees [a -'a' ]=mapWordToTree (trees [a -'a' ],word ,1 );
52+ }else {
53+ if (1 ==word .length ()){
54+ trees [a -'a' ].end =true ;
55+ return ;
56+ }
57+ trees [a -'a' ]=mapWordToTree (trees [a -'a' ],word ,1 );
58+ }
59+ //System.out.println(trees[a-'a']);
3060 }
61+ public boolean searchWordInTree (TrieNode t , String word , int i ){
62+ char a =word .charAt (i );
63+ TrieNode m =t .nexts [a -'a' ];
64+ if (m !=null ){
65+
66+ if (i ==word .length ()-1 ){
67+ ans =true ;
68+ if (m .end ){
69+ return true ;
70+ }else {
71+ return false ;
72+ }
73+ }
74+ return searchWordInTree (m ,word , i +1 );
3175
32- private void insert (String word , TrieNode root , int idx ) {
33- if (idx == word .length ()) {
34- root .isWord = true ;
35- return ;
36- }
37- int index = word .charAt (idx ) - 'a' ;
38- if (root .children [index ] == null ) {
39- root .children [index ] = new TrieNode ();
4076 }
41- insert ( word , root . children [ index ], idx + 1 ) ;
77+ return false ;
4278 }
43-
44- // Returns if the word is in the trie.
4579 public boolean search (String word ) {
46- return search (word , root , 0 );
80+ char a =word .charAt (0 );
81+ if (trees [a -'a' ]==null ){
82+ return false ;
83+ }else {
84+ if (1 ==word .length ()){
85+ if (trees [a -'a' ].end ){
86+ return true ;
87+ }else {
88+ return false ;
89+ }
90+ }
91+ return searchWordInTree (trees [a -'a' ],word ,1 );
92+ }
4793 }
4894
49- private boolean search (String word , TrieNode root , int idx ) {
50- if (idx == word .length ()) {
51- startWith = true ;
52- return root .isWord ;
53- }
54- int index = word .charAt (idx ) - 'a' ;
55- if (root .children [index ] == null ) {
56- startWith = false ;
95+ public boolean startsWith (String prefix ) {
96+ char a =prefix .charAt (0 );
97+ ans =false ;
98+ if (trees [a -'a' ]==null ){
5799 return false ;
100+ }else {
101+ if (1 ==prefix .length ()){
102+ return true ;
103+ }
104+ searchWordInTree (trees [a -'a' ],prefix ,1 );
58105 }
59- return search ( word , root . children [ index ], idx + 1 ) ;
106+ return ans ;
60107 }
61108
62- // Returns if there is any word in the trie
63- // that starts with the given prefix.
64- public boolean startsWith (String prefix ) {
65- search (prefix );
66- return startWith ;
109+ class TrieNode {
110+ char val ;
111+ boolean end =false ;
112+ TrieNode [] nexts =new TrieNode [26 ];
113+ TrieNode (char val ){
114+ this .val =val ;
115+ }
116+ @ Override public String toString (){
117+ return val +" " +nexts +" " +end ;
118+ }
67119 }
68120}
69121
@@ -74,3 +126,11 @@ public boolean startsWith(String prefix) {
74126 * boolean param_2 = obj.search(word);
75127 * boolean param_3 = obj.startsWith(prefix);
76128 */
129+
130+ /*
131+ * Your Trie object will be instantiated and called as such:
132+ * Trie obj = new Trie();
133+ * obj.insert(word);
134+ * boolean param_2 = obj.search(word);
135+ * boolean param_3 = obj.startsWith(prefix);
136+ */
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