<p>Write a function to find the longest common prefix string amongst an array of strings.</p>

<p>If there is no common prefix, return an empty string <code>&quot;&quot;</code>.</p>

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

<pre>
<strong>Input:</strong> strs = [&quot;flower&quot;,&quot;flow&quot;,&quot;flight&quot;]
<strong>Output:</strong> &quot;fl&quot;
</pre>

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

<pre>
<strong>Input:</strong> strs = [&quot;dog&quot;,&quot;racecar&quot;,&quot;car&quot;]
<strong>Output:</strong> &quot;&quot;
<strong>Explanation:</strong> There is no common prefix among the input strings.
</pre>

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

<ul>
	<li><code>1 &lt;= strs.length &lt;= 200</code></li>
	<li><code>0 &lt;= strs[i].length &lt;= 200</code></li>
	<li><code>strs[i]</code> consists of only lowercase English letters.</li>
</ul>

class Node{
    public:
        char val;
        vector<Node*>children;
        bool isend;
        Node(char val): val(val){
            children = vector<Node*>(26, nullptr);
            isend=false;
        }
};
class Solution {
public:
    string longestCommonPrefix(vector<string>& strs) {
        if(strs.size()==0) return "";
        Node* trie = new Node(' ');
        for(auto str: strs){
            Node* curr = trie;
            for(int i=0;i<str.length();i++){
                if(curr->children[str[i]-'a']==nullptr){
                    curr->children[str[i]-'a'] = new Node(str[i]);
                }
                curr=curr->children[str[i]-'a'];
            }
            curr->isend=true;
        }
        Node* curr = trie;
        string ans="";
        while(curr!=nullptr){
            if(curr->isend==true)
                break;
            int count = 0;
            Node* temp=nullptr;
            for(int i=0;i<26;i++){
                if(count>1) break;
                if(curr->children[i]!=nullptr){
                    count++;
                    temp=curr->children[i];
                }
            }
            if(count!=1) break;
            ans+=temp->val;
            curr = temp;
        }
        return ans;
    }
};
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