<p><strong>HTML entity parser</strong> is the parser that takes HTML code as input and replace all the entities of the special characters by the characters itself.</p>

<p>The special characters and their entities for HTML are:</p>

<ul>
	<li><strong>Quotation Mark:</strong> the entity is <code>&amp;quot;</code> and symbol character is <code>&quot;</code>.</li>
	<li><strong>Single Quote Mark:</strong> the entity is <code>&amp;apos;</code> and symbol character is <code>&#39;</code>.</li>
	<li><strong>Ampersand:</strong> the entity is <code>&amp;amp;</code> and symbol character is <code>&amp;</code>.</li>
	<li><strong>Greater Than Sign:</strong> the entity is <code>&amp;gt;</code> and symbol character is <code>&gt;</code>.</li>
	<li><strong>Less Than Sign:</strong> the entity is <code>&amp;lt;</code> and symbol character is <code>&lt;</code>.</li>
	<li><strong>Slash:</strong> the entity is <code>&amp;frasl;</code> and symbol character is <code>/</code>.</li>
</ul>

<p>Given the input <code>text</code> string to the HTML parser, you have to implement the entity parser.</p>

<p>Return <em>the text after replacing the entities by the special characters</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> text = &quot;&amp;amp; is an HTML entity but &amp;ambassador; is not.&quot;
<strong>Output:</strong> &quot;&amp; is an HTML entity but &amp;ambassador; is not.&quot;
<strong>Explanation:</strong> The parser will replace the &amp;amp; entity by &amp;
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> text = &quot;and I quote: &amp;quot;...&amp;quot;&quot;
<strong>Output:</strong> &quot;and I quote: \&quot;...\&quot;&quot;
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= text.length &lt;= 10<sup>5</sup></code></li>
	<li>The string may contain any possible characters out of all the 256 ASCII characters.</li>
</ul>

class Solution {
public:
    string entityParser(string text) {
        
        int n = text.size();
        int sliding;
        vector<int> marked(n, 1);
        sliding = 7;
        for (int start = 0; start <= n - sliding; start++){
            int back = start + sliding - 1;
            string sub = text.substr(start, back - start + 1);
            if (sub.compare("&frasl;") == 0){
                text[start] = '/';
                for (int i = start + 1; i <= back; i++){
                    marked[i] = -1;
                }
            }
        }
        sliding = 6;
        for (int start = 0; start <= n - sliding; start++){
            int back = start + sliding - 1;
            string sub = text.substr(start, back - start + 1);
            if (sub.compare("&quot;") == 0){
                text[start] = '"';
                for (int i = start + 1; i <= back; i++){
                    marked[i] = -1;
                }
            }
            else if (sub.compare("&apos;") == 0){
                text[start] = '\'';
                for (int i = start + 1; i <= back; i++){
                    marked[i] = -1;
                }
            }
        }
        sliding = 5;
        for (int start = 0; start <= n - sliding; start++){
            int back = start + sliding - 1;
            string sub = text.substr(start, back - start + 1);
            if (sub.compare("&amp;") == 0){
                text[start] = '&';
                for (int i = start + 1; i <= back; i++){
                    marked[i] = -1;
                }
            }
        }
        sliding = 4;
        for (int start = 0; start <= n - sliding; start++){
            int back = start + sliding - 1;
            string sub = text.substr(start, back - start + 1);
            if (sub.compare("&gt;") == 0){
                text[start] = '>';
                for (int i = start + 1; i <= back; i++){
                    marked[i] = -1;
                }
            }
            else if (sub.compare("&lt;") == 0){
                text[start] = '<';
                for (int i = start + 1; i <= back; i++){
                    marked[i] = -1;
                }
            }
        }
        int index = 0;
        for (int i = 0; i < n; i++){
            if (marked[i] == 1){
                text[index] = text[i];
                index++;
            }
        }
        text.resize(index);
        return text;
    }
};
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