208.Implement Trie (Prefix Tree)
class TrieNode {
public:
TrieNode* children[26];
bool isWord;
TrieNode(){
isWord = false;
for(int i =0; i<26;++i){
children[i] = NULL;
}
}
};
class Trie {
private:
TrieNode* root;
public:
/** Initialize your data structure here. */
Trie() {
root = new TrieNode();
}
/** Inserts a word into the trie. */
void insert(string word) {
TrieNode * temp =root;
for(int i = 0; i < word.size(); ++i) {
if(!temp->children[word[i]-'a']){
temp->children[word[i]-'a'] = new TrieNode();
}
temp=temp->children[word[i]-'a'];
}
temp->isWord = true;
}
/** Returns if the word is in the trie. */
bool search(string word) {
TrieNode * temp =root;
for(int i = 0; i < word.size(); ++i) {
if(!temp->children[word[i]-'a']){
return false;
}
temp=temp->children[word[i]-'a'];
}
return temp->isWord;
}
/** Returns if there is any word in the trie that starts with the given prefix. */
bool startsWith(string prefix) {
TrieNode * temp =root;
for(int i = 0; i < prefix.size(); ++i) {
if(!temp->children[prefix[i]-'a']){
return false;
}
temp=temp->children[prefix[i]-'a'];
}
return true;
}
};
/**
* Your Trie object will be instantiated and called as such:
* Trie obj = new Trie();
* obj.insert(word);
* bool param_2 = obj.search(word);
* bool param_3 = obj.startsWith(prefix);
*/