Implement Trie and it's supporting functions - 

```
* insert(word) - Insert a word in the trie, 
* search(word) - search if the word exists in the trie, and 
* startsWith(prefix) - search if there exist any word which starts with <prefix>.
```

Clarified if we are only dealing with lowercase alphabets. Yes.

I implemented `TrieNode` like below.

```
class TrieNode{
    int val;
    vector<TrieNode*> children;
};
```

Follow up question.
Currently, we are occupying 26 space for children. How can we optimize it ?
Suggested to use a Map instead of vector.

```
class TrieNode{
    int val;
    unordered_map<int, TrieNode*> child;
};

// int denotes 0 for 'a', 1 for 'b', or you can do char too in this case. 
// I chose int.
```
Looks good.

**Bonus question.**

Implement

```
longestPrefixWhichStartsWithPrefix(prefix) - find the longest prefix which starts with a given prefix.
```

prefix = abc
words = [abcdef, abcdeg] -> abcde

Cleared the round.

Implement Trie and it's supporting functions -Clarified if we are only dealing with lowercase alphabets. Yes.I implemented TrieNode like below.Follow up question.
Currently, we are occupying 26 space for children. How can we optimize it ?
Suggested t