# Description

Implement a trie with insert, search, and startsWith methods.

Note:
You may assume that all inputs are consist of lowercase letters a-z.

The original problem is here.

The original code is here.

# My Solution

I solve this problem in C++, as below:

``````/*
*Implement Trie (Prefix Tree)
*Author: shuaijiang
*Email: zhaoshuaijiang8@gmail.com
*/
#include<iostream>
#include<vector>
#include<map>
#include<sstream>
#include<math.h>
using namespace std;

class TrieNode {
public:
// Initialize your data structure here.
bool iskey;
TrieNode* childern[26];
TrieNode() {
for(int i=0;i<26;i++)
childern[i] = NULL;
iskey = false;
}
};

class Trie {
public:
Trie() {
root = new TrieNode();
}

// Inserts a word into the trie.
void insert(string word) {
int len = word.size();
TrieNode * node = root;
char ch;
for(int i=0;i<len;++i) {
ch = word[i];
if(node->childern[ch - 'a'] == NULL)
node->childern[ch - 'a'] = new TrieNode();
if(i==len-1)
node->childern[ch-'a']->iskey = true;
node = node->childern[ch-'a'];
}
}

// Returns if the word is in the trie.
bool search(string word) {
int len = word.size();
TrieNode * node = root;
char ch;
for(int i=0;i<len;++i){
ch = word[i];
if(node->childern[ch-'a'] == NULL)
return false;
if(i==len-1){
if(node->childern[ch-'a']->iskey == true)
return true;
else
return false;
}
node = node->childern[ch-'a'];
}
}

// Returns if there is any word in the trie
// that starts with the given prefix.
bool startsWith(string prefix) {
int len = prefix.size();
TrieNode * node = root;
char ch;
for(int i=0;i<len;++i){
ch = prefix[i];
if(node->childern[ch-'a'] == NULL)
return false;
node = node->childern[ch-'a'];
}
return true;
}

private:
TrieNode* root;
};

// Your Trie object will be instantiated and called as such:
// Trie trie;
// trie.insert("somestring");
// trie.search("key");
``````