# Longest substring withought repeating character leetcode solution.

Given a string s, find the length of the longest substring without repeating characters.

**Example 1:**

Input: s = "abcabcbb"

Output: 3

Explanation: The answer is "abc", with the length of 3.

**Example 2:**

Input: s = "bbbbb"

Output: 1

Explanation: The answer is "b", with the length of 1.

**Example 3:**

Input: s = "pwwkew"

Output: 3

Explanation: The answer is "wke", with the length of 3.

Notice that the answer must be a substring, "pwke" is a subsequence and not a substring.

**Constraints:**

0 <= s.length <= 5 * 104

s consists of English letters, digits, symbols and spaces.

```
class Solution {
public int lengthOfLongestSubstring(String s) {
int left =0;
int maxcount = 0;
Set<Character> set = new HashSet<>();
for(int right = 0; right < s.length(); right++){
while(set.contains(s.charAt(right))){
set.remove(s.charAt(left++));
}
set.add(s.charAt(right));
maxcount = Math.max(maxcount, right - left +1);
}
return maxcount;
}
}
```

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