<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) {
        if (s.length() <= 1) {
            return s.length();
        }
        int res = 0;
        for (int i = 0; i < s.length(); i++) {
            for (int j = i; j < s.length(); j++) {
                // cout << res << endl;
                if (res >= 95) {
                    break;
                }
                if (j - i + 1 <= res) {
                    continue;
                }
                vector<bool>seen (256, false);
                bool dupe = false;
                for (int k = i; k < j + 1; k++) {
                    if (seen[s[k]]) {
                        dupe = true;
                        break;
                    }
                    seen[s[k]] = true;
                }
                if (!dupe) {
                    res = max(res, j - i + 1);
                }
            }
        }
        return res;
    }
};
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