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Trie.java
65 lines (50 loc) · 1.59 KB
/
Trie.java
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// https://leetcode.com/problems/implement-trie-prefix-tree/
class Trie {
TrieNode root;
public Trie() {
root = new TrieNode();
}
public void insert(String word) {
TrieNode crawl = root;
int n = word.length();
for (int i = 0; i < n; i++) {
int level = word.charAt(i) - 97;
if (crawl.children[level] == null) crawl.children[level] = new TrieNode();
crawl = crawl.children[level];
}
crawl.isEnd = true;
}
public boolean search(String word) {
TrieNode crawl = root;
int n = word.length();
for (int i = 0; i < n; i++) {
int level = word.charAt(i) - 97;
TrieNode child = crawl.children[level];
if (child == null) return false;
crawl = child;
}
return crawl.isEnd;
}
public boolean startsWith(String word) {
TrieNode crawl = root;
int n = word.length();
for (int i = 0; i < n; i++) {
int level = word.charAt(i) - 97;
TrieNode child = crawl.children[level];
if (child == null) return false;
crawl = child;
}
return true;
}
class TrieNode {
TrieNode[] children = new TrieNode[26];
boolean isEnd = false;
}
}
/**
* Your Trie object will be instantiated and called as such:
* Trie obj = new Trie();
* obj.insert(word);
* boolean param_2 = obj.search(word);
* boolean param_3 = obj.startsWith(prefix);
*/