<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:
        char data;
        TrieNode* children[26];
        bool isTerminal;

    TrieNode(char ch){
        data = ch;
        for(int i=0; i<26; i++) children[i] = NULL;
        isTerminal = false;
    }
};

class Trie{
    public:
        TrieNode* root;
    
    Trie(){
        root = new TrieNode('\0');
    }

    void insertWordUtil(TrieNode* root, string word){
        //Base case
        if(word.length() == 0){
            root->isTerminal = true;
            return;
        }

        int index = word[0] - 'a';
        TrieNode* child;

        if(root->children[index] != NULL){
            child = root->children[index];
        }else{
            child = new TrieNode(word[0]);
            root->children[index] = child;
        }

        insertWordUtil(child, word.substr(1));
    }

    void insertWord(string &word){
        insertWordUtil(root, word);
    }

    string searchWord(const string &word) {
        TrieNode* node = root;
        string result = "";

        for (int i = 0; i < word.size(); i++) {
            if (node->children[word[i] - 'a'] != NULL) {
                result += word[i];
                node = node->children[word[i] - 'a'];

                if (node->isTerminal) {
                    return result; 
                }
            } else {
                break;
            }
        }

        return word;
    }
};
class Solution {
public:
    string replaceWords(vector<string>& dictionary, string sentence) {
        Trie* trie = new Trie();
        for(string& root : dictionary) trie->insertWord(root);

        string ans = "";
        
        int n = sentence.size();
        for(int i =0; i<n; i++){
            string word = "";
            while(i<n && sentence[i] != ' '){
                word += sentence[i];
                i++;
            }

            ans += trie->searchWord(word) + " ";
        }

        ans.pop_back();
        return ans;
    }
};
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