<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 Node{
    public:
    Node *link[26];
    bool isleaf;

};
class Solution {
public:
    Node* root=new Node();
    void insert(string word) {
        Node* curr=root;
        for(int i=0;i<word.size();i++){
            if(curr->link[word[i]-'a']==NULL){
                curr->link[word[i]-'a']=new Node();
            }
            curr=curr->link[word[i]-'a'];
        }
        curr->isleaf=true;
    }
    bool search(string word) {
        Node* curr=root;
        for(int i=0;i<word.size();i++){
            if(curr->link[word[i]-'a']==NULL){
                return false;
            }
            curr=curr->link[word[i]-'a'];
        }
        return curr->isleaf==true;
    }
    string replaceWords(vector<string>& dic, string s) {
        
        for(int i=0;i<dic.size();i++){
            insert(dic[i]);
        }

        stringstream ss(s);
        string p;
        // getline(ss,p,' ');
        string ans;
        while(ss>>p){
          string q;
          for(int i=0;i<p.size();i++){
            q+=p[i];
            if(search(q)){
                break;
            }
          }
          ans+=q;
          ans+=' ';
        }
        ans.pop_back();
        return ans;
    }
};
513657