<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>

using namespace std;
class Solution {
public:
    int lengthOfLongestSubstring(string s) {
    int maxsize=0,cur=0;
    unordered_map<char,pair<int,int>> alphabet;
    for (int i=0;i<s.size();i++){
        if (alphabet[s[i]].first==0){
            alphabet[s[i]].first++;
            alphabet[s[i]].second=i;
            cur++;
        }
        else {
            maxsize=max(cur,maxsize);
            i=alphabet[s[i]].second;
            alphabet.clear();
            cur=0;
        }
    }
    maxsize=max(cur,maxsize);
    return maxsize;
}
};
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