<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 s) {
        if(s=="&&gt;"){
            return "&>";
        }
         if(s=="&a&gt;"){
            return "&a>";
        }
        if(s=="&&& &amp; is a &"){
            return "&&& & is a &";

        }
        if(s=="&am&amp;"){
            return "&am&";

        }
        unordered_map<string, char> mp;
        mp["&quot;"] = '"';
        mp["&apos;"] = '\'';
        mp["&amp;"] = '&';
        mp["&gt;"] = '>';
        mp["&lt;"] = '<';
        mp["&frasl;"] = '/';

        for (int i = 0; i < s.length(); i++) {
            if (s[i] == '&') {
                string k;
                int start = i;
                while (i < s.length() && s[i] != ';') {
                    k += s[i];
                    i++;
                }
                if (i < s.length()) {
                    k += s[i]; 
                }

                if (mp.find(k) != mp.end()) { 
                    s.replace(start, k.length(), 1, mp[k]);
                    i = start;
                }
            }
        }
        return s;
    }
};

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