<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 longest = 0;
        string curr;
        unordered_map<char, int> duplicates;

        for (int i = 0; i < s.size(); i++) {
            curr += s[i];

            if (duplicates.find(s[i]) != duplicates.end()) {
                int duplicate_index = duplicates[s[i]];

                string prefix = curr.substr(0, duplicate_index + 1);

                if (curr.size() - duplicate_index - 1 > 0) {
                    curr = curr.substr(duplicate_index + 1, curr.size() - duplicate_index - 1);
                } else {
                    curr = s[i];
                }

                duplicates = unordered_map<char, int>();

                for (int j = 0; j < curr.size(); j++) {
                    duplicates[curr[j]] = j;
                }
            }

            duplicates[s[i]] = curr.size() - 1;

            longest = max((int) curr.size(), longest);
        }

        return longest;
    }
};
246000