<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>

from collections import defaultdict
class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        char_set = set()
        max_length = 0
        l = 0
        for r in range(len(s)):
            while s[r] in char_set:
                char_set.remove(s[l])
                l += 1
            char_set.add(s[r])
            max_length = max(max_length, r - l + 1)
        return max_length
    
        # start, current = 0, 0
        # maxSubStr = 0
        # charset = set()
        # chardict = defaultdict(list)
        # while current < len(s):
        #     c = s[current]
        #     chardict[c].append(current)
        #     if (c not in charset):
        #         charset.add(c)
        #         current += 1
        #         maxSubStr =  max(maxSubStr, current-start)
        #         # print(f'{s[start:current]} : {current-start} {start=} | {current=}')
        #     else:
        #         new_index = chardict[c][-2] + 1
        #         # if (current != new_index):
        #         #     current = new_index
        #         # else:
        #         #     current = current + 1
        #         current = new_index
        #         start = current
        #         charset.clear()
        #         # print(f'({c}) already seen | {current=} {new_index=}')
        # return maxSubStr
            





        
16300