<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 ind, count =0, max=0;
        vector<int> ch(256, -1);
        if(s.length()==1) return 1;
        for(int i=0; i<s.length(); i++){
            //cout<<"i= "<<i<<endl;
            if(ch[s[i]]<0){
                //cout<<"not found\n";
                ch[s[i]]=i;
                count++;
            }
            else{
                //cout<<"found!!\nat "<<ch[s[i]]<<"\ncount: "<<count<<" max: "<<max<<endl;
                if(count>max) max=count;
                i=ch[s[i]];
                count=0;
                ch = vector<int>(256, -1);
            }
        }
        if(count>max) max=count;
        return max;
    }
};
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