<p>In English, we have a concept called <strong>root</strong>, which can be followed by some other word to form another longer word - let&#39;s call this word <strong>derivative</strong>. For example, when the <strong>root</strong> <code>&quot;help&quot;</code> is followed by the word <code>&quot;ful&quot;</code>, we can form a derivative <code>&quot;helpful&quot;</code>.</p>

<p>Given a <code>dictionary</code> consisting of many <strong>roots</strong> and a <code>sentence</code> consisting of words separated by spaces, replace all the derivatives in the sentence with the <strong>root</strong> forming it. If a derivative can be replaced by more than one <strong>root</strong>, replace it with the <strong>root</strong> that has <strong>the shortest length</strong>.</p>

<p>Return <em>the <code>sentence</code></em> after the replacement.</p>

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

<pre>
<strong>Input:</strong> dictionary = [&quot;cat&quot;,&quot;bat&quot;,&quot;rat&quot;], sentence = &quot;the cattle was rattled by the battery&quot;
<strong>Output:</strong> &quot;the cat was rat by the bat&quot;
</pre>

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

<pre>
<strong>Input:</strong> dictionary = [&quot;a&quot;,&quot;b&quot;,&quot;c&quot;], sentence = &quot;aadsfasf absbs bbab cadsfafs&quot;
<strong>Output:</strong> &quot;a a b c&quot;
</pre>

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

<ul>
	<li><code>1 &lt;= dictionary.length &lt;= 1000</code></li>
	<li><code>1 &lt;= dictionary[i].length &lt;= 100</code></li>
	<li><code>dictionary[i]</code> consists of only lower-case letters.</li>
	<li><code>1 &lt;= sentence.length &lt;= 10<sup>6</sup></code></li>
	<li><code>sentence</code> consists of only lower-case letters and spaces.</li>
	<li>The number of words in <code>sentence</code> is in the range <code>[1, 1000]</code></li>
	<li>The length of each word in <code>sentence</code> is in the range <code>[1, 1000]</code></li>
	<li>Every two consecutive words in <code>sentence</code> will be separated by exactly one space.</li>
	<li><code>sentence</code> does not have leading or trailing spaces.</li>
</ul>

class Solution {
public:
    //M-1
    // string findroot(string &word ,unordered_set<string>&st)
    // {
    //     for(int len = 1;len<=word.length();len++)
    //     {
    //         string root = word.substr(0 , len);
    //         if(st.count(root) == 1)
    //         {
    //             return root;
    //         }
    //     }
    //     return word;
    // }
    // string replaceWords(vector<string>& dictionary, string sentence) {
    //     string ans;
    //     //O(1) k liye
    //     unordered_set<string> st(dictionary.begin(),dictionary.end());

    //     stringstream ss(sentence);
    //     string word;
    //     while(getline(ss,word,' '))
    //     {
    //         ans = ans + findroot(word,st) + " "; 
    //     }
    //     ans.pop_back();
    //     return ans;
    // }

    //M-2
    class TrieNode{
    public:
        bool isEnd;
        TrieNode* child[26];

        TrieNode()
        {
            this->isEnd = false;
            for(int i = 0;i<26;i++)
            {
                this->child[i] = NULL;
            }
        } 
    };
    TrieNode* root;
    void insert(string& word)
    {
        TrieNode* crawler = root;
        for(int i = 0;i<word.length();i++)
        {
            int idx = word[i] - 'a';
            if(crawler->child[idx] == NULL)
            {
                crawler->child[idx] = new TrieNode();
            }
            crawler = crawler->child[idx];
        }
        crawler->isEnd = true;
    }
    string search_root(string& word)
    {
        TrieNode* crawler = root;
        for(int i = 0;i<word.length();i++)
        {
            int idx = word[i] - 'a';
            if(crawler->child[idx] == NULL)
                return word;

            crawler = crawler->child[idx];
            if(crawler->isEnd == true)
            {
                return word.substr(0 , i+1);
            }    
        }
        return word;
    }
    string replaceWords(vector<string>& dictionary, string sentence) 
    {
        root = new TrieNode();
        for(string& word : dictionary)
        {
            insert(word);
        }

        stringstream ss(sentence);
        string word;
        string ans;
        while(getline(ss,word,' '))
        {
            ans = ans +  search_root(word) + " ";
        }
        ans.pop_back();
        return ans;
    }
};
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