<p>Given an array of strings <code>words</code> representing an English Dictionary, return <em>the longest word in</em> <code>words</code> <em>that can be built one character at a time by other words in</em> <code>words</code>.</p>

<p>If there is more than one possible answer, return the longest word with the smallest lexicographical order. If there is no answer, return the empty string.</p>

<p>Note that the word should be built from left to right with each additional character being added to the end of a previous word.&nbsp;</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> words = [&quot;w&quot;,&quot;wo&quot;,&quot;wor&quot;,&quot;worl&quot;,&quot;world&quot;]
<strong>Output:</strong> &quot;world&quot;
<strong>Explanation:</strong> The word &quot;world&quot; can be built one character at a time by &quot;w&quot;, &quot;wo&quot;, &quot;wor&quot;, and &quot;worl&quot;.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> words = [&quot;a&quot;,&quot;banana&quot;,&quot;app&quot;,&quot;appl&quot;,&quot;ap&quot;,&quot;apply&quot;,&quot;apple&quot;]
<strong>Output:</strong> &quot;apple&quot;
<strong>Explanation:</strong> Both &quot;apply&quot; and &quot;apple&quot; can be built from other words in the dictionary. However, &quot;apple&quot; is lexicographically smaller than &quot;apply&quot;.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= words.length &lt;= 1000</code></li>
	<li><code>1 &lt;= words[i].length &lt;= 30</code></li>
	<li><code>words[i]</code> consists of lowercase English letters.</li>
</ul>

struct Node{
    Node* arr[26];
    bool flag=false;
    bool containsKey(char key){
        if(arr[key-'a']!=NULL){
            return true;
        }else{
            return false;
        }
    }
    void put(char ch,Node* newNode){
        arr[ch-'a']=newNode;
    }
    Node* get(char ch){
        return arr[ch-'a'];
    }
    void setEnd(){
        flag=true;
    }
    bool isEnd(){
        return flag;
    }

};

class Trie {
private:
    Node* root;
public:
    Trie() {
        root=new Node();
        
    }
    
    void insert(string word) {
        Node* node=root;
        for(int i=0;i<word.length();i++){
            if(!node->containsKey(word[i])){
                node->put(word[i],new Node());

            }
            node=node->get(word[i]);

        }
        node->setEnd();
        
    }
    
    bool search(string word) {
        Node* node=root;
        for(int i=0;i<word.length()-1;i++){
            if(!node->containsKey(word[i])){
                return false;
            }
            node=node->get(word[i]);
            if(!node->isEnd()){
                return false;
            }
        }
        return true;
        
    }
    
    
};
class Solution {
public:
    bool static comp(string a,string b){
        return a.length()<b.length();
    }

    string longestWord(vector<string>& words) {
        Trie trie;
        int n=words.size();
        int maxlen=0;
        string ans="";
        sort(words.begin(),words.end(),comp);
        for(int i=0;i<n;i++){
            if(trie.search(words[i])){
                if(words[i].length()==maxlen){
                    if(words[i]<ans){
                        ans=words[i];
                    }
                }
                if(words[i].length()>maxlen){
                    maxlen=words[i].length();
                    ans=words[i];
                }
            }
            trie.insert(words[i]);
            
        }
        return ans;

        
    }
};
52628