<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 Trie {
    Trie* child[101] {};
    bool isLeaf {};
public:
    Trie() {
        memset(child,0 ,sizeof child);
    }
    void insert(string &s , int idx = 0) {
        if(idx == (int)s.size())
            isLeaf = true;
        else {
            int pos = s[idx] - 'a';
            if(!child[pos])
                child[pos] = new Trie();
            child[pos]->insert(s,idx + 1);
        }
    }
    string first_word_prefix(string &str, int idx) {
    Trie* cur = this;
    for(idx = 0 ; idx < (int)str.size() ; ++idx) {
        int pos = str[idx] - 'a';
        if(!cur->child[pos])
            return str;
        cur = cur->child[pos];
        if(cur->isLeaf)
            return str.substr(0,idx + 1);
    }
    return str;
}
};
class Solution {
public:
    string replaceWords(vector<string>& dictionary, string sentence) {
        Trie T;
        for(auto& s : dictionary)
            T.insert(s);
        string res;
        stringstream s(sentence);
        string word;
        while(s >> word) {
            string c;
            c = T.first_word_prefix(word,0);
            if(c.empty())
                res += word;
            else
                res += c;
            res += ' ';
        }
        res.pop_back();
        return res;
    }
};
132017