<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>

struct Node{
    Node* links[26];
    bool flag=false;

    bool containsKey(char ch) {
        return links[ch - 'a'] != NULL;
    }

    void put(char ch, Node*node){
        links[ch-'a']=node;
    }

    Node* get(char ch){
        return links[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();i++){
            if(!node->containsKey(word[i])){
                return false;
            }
            node=node->get(word[i]);
        }
        return node->isEnd();
    }
    
    bool startsWith(string prefix) {
        Node *node = root;
        for(int i=0;i<prefix.length();i++){
            if(!node->containsKey(prefix[i])){
                return false;
            }
            node=node->get(prefix[i]);
        }
        return true;
    }
};

class Solution {
public:
    string replaceWords(vector<string>& dictionary, string sentence) {
        // map<string,int> mp;
        // for(auto it:dictionary){
        //     mp[it]=1;
        // }
        Trie trie;
        for(auto it:dictionary){
            trie.insert(it);
        }
        string final="";
        for(int i=0;i<sentence.size();i++){
            string temp="",root="";
            while(sentence[i]!=' '&&i<sentence.size()){
                temp+=sentence[i];
                i++;
                
                if(trie.search(temp)){
                    root=temp;
                    break;
                }
            }
            if(root!=""){
                final+=root;
            }
            else{
                final+=temp;
            }
            
            while(sentence[i]!=' '&&i<sentence.size()){
                i++;
            }
            if(i!=sentence.size()) final+=' ';
        }
        return final;
    }
};
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