<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 n = s.size();
        if (n < 1) return n;
        int res = 1;
        vector<int> dp(n, 1); //dp[i] represents longest substring starting at index i (fixed left endpoint)
    unordered_map<char, int> freqs;


for (int lo = 0; lo < n; lo++) {
    freqs.clear();
    // cout << "lo: " << lo << endl;
    char fixed_char = s[lo];
    freqs[fixed_char] += 1;
    int curr_length = 1;
    for (int hi = lo+1; hi > lo && hi < n; hi++) {
        // cout << "hi: " << hi << endl;
        char curr_char = s[hi];
        freqs[curr_char] += 1;
        if (freqs[curr_char] > 1) {
            dp[lo] = max(dp[lo], curr_length);
            res = max(curr_length, res);
            curr_length = 0;
            break;
        }
        curr_length += 1;
        res = max(curr_length, res);

    }
}
       
return res;
    }
};
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