Implement a trie with insert, search, and startsWith methods.
Example:
Trie trie = new Trie();
trie.insert("apple");
trie.search("apple"); // returns true
trie.search("app"); // returns false
trie.startsWith("app"); // returns true
trie.insert("app");
trie.search("app"); // returns true
Note:
You may assume that all inputs are consist of lowercase letters a-z. All inputs are guaranteed to be non-empty strings.
class TrieNode{
public Map<Character,TrieNode> map=new HashMap<>();
public boolean isEnd=false;
public void putChildIfAbsent(char ch){
map.putIfAbsent(ch,new TrieNode());
}
public TrieNode getChild(char ch){
return map.get(ch);
}
}
class Trie {
TrieNode root = new TrieNode();
public void insert(String word) {
TrieNode curr=root;
for(char ch:word.toCharArray()){
curr.putChildIfAbsent(ch);
curr=curr.getChild(ch);
}
curr.isEnd=true;
}
public boolean search(String word) {
TrieNode curr=root;
for(char ch:word.toCharArray()){
curr=curr.getChild(ch);
if(curr==null) return false;
}
return curr.isEnd;
}
public boolean startsWith(String prefix) {
TrieNode curr=root;
for(char ch:prefix.toCharArray()){
curr=curr.getChild(ch);
if(curr==null) return false;
}
return true;
}
}
/**
* 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);
*/