<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:
    class Trie{
        public:
        bool end;
        vector<Trie*>child;
        Trie(){
            end=false;
            for(int i=0;i<26;i++)
                child.push_back(NULL);
        }
    };
    void insert(Trie* trie, string w){
              Trie*temp=trie;
              int n=w.size();
              for(int i=0;i<n;i++){
                  if(!temp->child[w[i]-'a'])
                      temp->child[w[i]-'a']=new Trie();
                  temp=temp->child[w[i]-'a'];
              }
              temp->end=true;
    }
    pair<bool,string> search(Trie*trie, string w){
             Trie*temp=trie;
             int n=w.size();
             string s="";
             for(int i=0;i<n;i++){
                 s+=w[i];
                 if(temp->child[w[i]-'a'])
                     temp=temp->child[w[i]-'a'];
                 else
                     return {false,s};
                 if(temp->end)
                     return {true,s};
             }
      return {temp->end,s};
    }
    string replaceWords(vector<string>& d, string s) {
               Trie* trie= new Trie();
               for(auto t: d)
                   insert(trie,t);
               int n=s.size();
               string ans="";
               for(int i=0;i<n;){
                    if(s[i]==' '){
                        ans+=' ';
                        i++;
                        continue;
                    }
                   string s1="";
                   int j=i;
                   while(j<n&&s[j]!=' ')
                        s1+=s[j++];
                   auto a= search(trie,s1);
                   if(a.first)
                       ans+=a.second;
                   else
                       ans+=s1;
                   i=j;
               }
    return ans;
    }
};
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