<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 {
    bool is_root = false;
    int child[26] = {};
};

class Solution {
public:
    string find_in_trie(const string& sentence, int& index) {
        int cur_in_trie = 0;
        string res;
        bool done_str = false;
        bool done_trie = false;
        do {
            if (!done_str) res += sentence[index];
            if (!done_trie) cur_in_trie = trie[cur_in_trie].child[sentence[index] - 'a'];
            if (trie[cur_in_trie].is_root) {
                done_str = true;
                done_trie = true;
            } else if (!cur_in_trie) {
                done_trie = true;
            }
            index++;
        } while (index < sentence.size() && sentence[index] != ' ');
        return res;
    }

    string replaceWords(vector<string>& dictionary, string sentence) {
        trie.push_back({});
        int index = 0;
        for (int i = 0; i < dictionary.size(); ++i) {
            int cur = 0;
            const char* c_str = dictionary[i].c_str();
            while (*c_str) {
                int child_index = *c_str - 'a';
                if (!trie[cur].child[child_index]) {
                    trie.push_back({});
                    ++index;
                    trie[cur].child[child_index] = index;
                }
                cur = trie[cur].child[child_index];
                c_str++;
            }
            trie[cur].is_root = true;
        }

        //cout << sentence << endl;

        int sentence_index = 0;
        string res;
        while (sentence[sentence_index]) {
            //cout << sentence_index << endl;
            string replaced = find_in_trie(sentence, sentence_index);
            //cout << replaced << endl;
            res = res + replaced;
            if (sentence_index < sentence.length()) {
                ++sentence_index;
                res += ' ';
            }
        }
        return res;
    }
    vector<TrieNode> trie;
};
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