<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 TrieNode{
    public:
    TrieNode* children[26];
    char value;
    bool isTerminal;
    TrieNode(char ch){
        this->value=ch;
        for(int i=0;i<26;i++){
            children[i]=NULL;
        }
        this->isTerminal=false;
    }

};
void insertWord(TrieNode*root, string word){
        if(word.length() == 0){
            root->isTerminal=true;
           return;
           
        }
        char ch = word[0];
        int index= ch -'a';
        TrieNode*child;
        if(root->children[index] != NULL){
            child= root->children[index];
        }else{
            child= new TrieNode(ch);
            root->children[index]=child;
        }
        insertWord(child,word.substr(1));
    }
    bool searchWord(TrieNode* root, string word,int& i){
        if(root->isTerminal){
            return true;
        }
        if(i >= word.length()){
            return root->isTerminal;
        }
        char ch = word[i++];
        int index= ch-'a';
        TrieNode*child;
        if(root->children[index] != NULL){
            child= root->children[index];
        }else{
            return false;
        }
        bool recKaAns = searchWord(child,word,i);
        return recKaAns;
    }


class Solution {
public:
    string replaceWords(vector<string>& dictionary, string sentence) {
        string ans;
        TrieNode*root = new TrieNode('-');
        for(auto d: dictionary){
            insertWord(root,d);
        }
        int start=0,end=0;
        while(end < sentence.size()){
            
            if(sentence[end] == ' ' || end == sentence.size()-1){
                 int i=0;
                int len = end == sentence.size()-1? sentence.length():end-start;
                string word = sentence.substr(start,len);
                bool gotIt = searchWord(root,word,i);
                int trieIndex = gotIt?i:-1;
                ans += trieIndex != -1 ? word.substr(0,trieIndex):word;
                if(sentence[end] == ' '){
                    ans+= ' ';
                }
                start=end+1;
            }
            end++;
        }
        
        
        return ans;
        
    }
};
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