-
Notifications
You must be signed in to change notification settings - Fork 56
/
Trie.java
68 lines (58 loc) · 1.88 KB
/
Trie.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
package g0201_0300.s0208_implement_trie_prefix_tree;
// #Medium #Top_100_Liked_Questions #Top_Interview_Questions #String #Hash_Table #Design #Trie
// #Level_2_Day_16_Design #Udemy_Trie_and_Heap
// #Big_O_Time_O(word.length())_or_O(prefix.length())_Space_O(N)
// #2022_06_28_Time_34_ms_(99.90%)_Space_51_MB_(94.92%)
@SuppressWarnings("java:S1104")
public class Trie {
private TrieNode root;
private boolean startWith;
private static class TrieNode {
// Initialize your data structure here.
public TrieNode[] children;
public boolean isWord;
public TrieNode() {
children = new TrieNode[26];
}
}
public Trie() {
root = new TrieNode();
}
// Inserts a word into the trie.
public void insert(String word) {
insert(word, root, 0);
}
private void insert(String word, TrieNode root, int idx) {
if (idx == word.length()) {
root.isWord = true;
return;
}
int index = word.charAt(idx) - 'a';
if (root.children[index] == null) {
root.children[index] = new TrieNode();
}
insert(word, root.children[index], idx + 1);
}
// Returns if the word is in the trie.
public boolean search(String word) {
return search(word, root, 0);
}
public boolean search(String word, TrieNode root, int idx) {
if (idx == word.length()) {
startWith = true;
return root.isWord;
}
int index = word.charAt(idx) - 'a';
if (root.children[index] == null) {
startWith = false;
return false;
}
return search(word, root.children[index], idx + 1);
}
// Returns if there is any word in the trie
// that starts with the given prefix.
public boolean startsWith(String prefix) {
search(prefix);
return startWith;
}
}