<p>Given a string <code>s</code>, find the length of the <strong>longest</strong> <span data-keyword="substring-nonempty"><strong>substring</strong></span> without repeating characters.</p>

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

<pre>
<strong>Input:</strong> s = &quot;abcabcbb&quot;
<strong>Output:</strong> 3
<strong>Explanation:</strong> The answer is &quot;abc&quot;, with the length of 3.
</pre>

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

<pre>
<strong>Input:</strong> s = &quot;bbbbb&quot;
<strong>Output:</strong> 1
<strong>Explanation:</strong> The answer is &quot;b&quot;, with the length of 1.
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;pwwkew&quot;
<strong>Output:</strong> 3
<strong>Explanation:</strong> The answer is &quot;wke&quot;, with the length of 3.
Notice that the answer must be a substring, &quot;pwke&quot; is a subsequence and not a substring.
</pre>

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

<ul>
	<li><code>0 &lt;= s.length &lt;= 5 * 10<sup>4</sup></code></li>
	<li><code>s</code> consists of English letters, digits, symbols and spaces.</li>
</ul>

class Solution {
public:
	int lengthOfLongestSubstring(string s) {
		int ctr_ret = 0;
		int ctr_tmp = 0;
		int string_size = s.size();
		list<char> used_char;
		for(int j=0; j<string_size; j++)
		{
			for(int i=j; i<string_size; i++)
			{
				bool repeated = false;
				char char_tmp = s[i];
				for(list<char>::iterator it=used_char.begin(); it!=used_char.end(); ++it)
				{
					if(char_tmp == *it)
					{
						repeated = true;
						break;
					}
				}
				if(repeated)
				{
					used_char.clear();
					if(ctr_tmp>ctr_ret) ctr_ret = ctr_tmp;
					ctr_tmp = 0;
                    break;
				}
				ctr_tmp++;
				used_char.push_front(char_tmp);
                if(ctr_tmp>ctr_ret) ctr_ret = ctr_tmp;
			}
			
		}
		
		return ctr_ret;
	}
};
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