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14-ImplementTriePrefix.java
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14-ImplementTriePrefix.java
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class Trie {
/**
* Initialize your data structure here.
*/
TrieNode root;
public Trie() {
root = new TrieNode();
}
/**
* Inserts a word into the trie.
*/
public void insert(String word) {
TrieNode temp = root;
boolean contains = true;
for (char ch : word.toCharArray()) {
if (contains && temp.containsKey(ch)) {
temp = temp.getKey(ch);
} else {
contains = false;
TrieNode newNode = new TrieNode();
temp.setKey(ch, newNode);
temp = newNode;
}
}
temp.setEnd(true);
}
/**
* Returns if the word is in the trie.
*/
public boolean search(String word) {
TrieNode temp = root;
for (char ch : word.toCharArray()) {
if (!temp.containsKey(ch))
return false;
temp = temp.getKey(ch);
}
if (temp.isEnd)
return true;
return false;
}
/**
* Returns if there is any word in the trie that starts with the given prefix.
*/
public boolean startsWith(String prefix) {
TrieNode temp = root;
for (char ch : prefix.toCharArray()) {
if (!temp.containsKey(ch))
return false;
temp = temp.getKey(ch);
}
return true;
}
}
class TrieNode {
TrieNode[] children;
boolean isEnd = false;
public TrieNode() {
children = new TrieNode[26];
}
public boolean containsKey(char ch) {
if (children[ch - 'a'] != null) return true;
return false;
}
public void setKey(char ch, TrieNode node) {
children[ch - 'a'] = node;
}
public TrieNode getKey(char ch) {
return children[ch - 'a'];
}
public boolean isEnd() {
return isEnd;
}
public void setEnd(boolean end) {
isEnd = end;
}
}
/**
* 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);
*/