<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 TrieNode{
    TrieNode *child[26];
    bool end;

    TrieNode(){
        end = false;
        for(int i=0;i<26;i++){
            child[i] = NULL;
        }
    }
};
class Solution {
public:
    TrieNode* root = new TrieNode();

    void store(string str){
        TrieNode* curr = root;

        for(char& c:str){
            if(curr->child[c-'a']==nullptr){
                curr->child[c-'a'] = new TrieNode();
            }
            curr = curr->child[c-'a'];
        }

        curr->end = true;
    }

    string find(string word){
        string ans;
        TrieNode* curr = root;

        for(char& ch:word){
            if(curr->end){
                break;
            }

            if(curr->child[ch-'a']!=nullptr){
                curr = curr->child[ch-'a'];
                ans+=ch;
            }
            else{
                return " ";
            }
        }


        return ans;
    }

    string replaceWords(vector<string>& dictionary, string sentence) {
        for(string& str:dictionary){
            store(str);
        }

        string temp;
        vector<string> ans;

        for(char& ch:sentence){
            if(ch!=' '){
                temp+=ch;
            }
            else{
                string chng = find(temp);
                if(chng==" "){
                    ans.push_back(temp);
                }
                else{
                    ans.push_back(chng);
                }
                temp = "";
            }
        }

        string chng = find(temp);
        if(chng==" "){
            ans.push_back(temp);
        }
        else{
            ans.push_back(chng);
        }


        string res;
        for(int i=0;i<ans.size()-1;i++){
            res+=ans[i];
            res+=" ";
        }
        res+=ans[ans.size()-1];

        return res;
    }
};
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