# Longest Substring Without Repeating Characters

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

## Example

For example, the longest substring without repeating letters for`"abcabcbb"`is`"abc"`, which the length is`3`.

For`"bbbbb"`the longest substring is`"b"`, with the length of`1`.

## Note

最大没有重复字符的滑动窗口，没出现过就一直右边界增加，左边移动的时候再把出现的置回0

## Code

```java
public class Solution {
    /**
     * @param s: a string
     * @return: an integer
     */
    public int lengthOfLongestSubstring(String s) {
        // write your code here
        int[] set = new int[256];
        int res = 0, len = s.length();

        int j = 0;
        for (int i = 0; i < len; i++) {
            while (j < len && set[s.charAt(j)] == 0) {
                set[s.charAt(j)]++;
                j++;
            }

            res = Math.max(res, j - i);
            set[s.charAt(i)] = 0;
        }

        return res;
    }
}
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://luj.gitbook.io/code/two-pointers/sliding-windows/longest-substring-without-repeating-characters.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.