# LeetCode - Longest Substring Without Repeating Characters

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 X 104
- s consists of English letters, digits, symbols, and spaces.

**Solution:**

```
class Solution {
public int lengthOfLongestSubstring(String s) {
int[] chars = new int[2 << 6];
int start = 0;
int end = 0;
int res = 0;
while(end < s.length()) {
char ch = s.charAt(end);
chars[ch]++;
while(chars[ch] > 1) {
char removeChar = s.charAt(start);
chars[removeChar]--;
start++;
}
res = Math.max(res, end - start + 1);
end++;
}
return res;
}
}
```