<h2><a href="https://leetcode.com/problems/longest-substring-without-repeating-characters/">3. Longest Substring Without Repeating Characters</a></h2><h3>Medium</h3><hr><div><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 = "abcabcbb"
<strong>Output:</strong> 3
<strong>Explanation:</strong> The answer is "abc", with the length of 3.
</pre>

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

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

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

<pre><strong>Input:</strong> s = "pwwkew"
<strong>Output:</strong> 3
<strong>Explanation:</strong> The answer is "wke", with the length of 3.
Notice that the answer must be a substring, "pwke" 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>
</div>