0003.无重复字符的最长子串

https://leetcode.cn/problems/longest-substring-without-repeating-characters/

方法一：滑动窗口

时间复杂度 $O(n)$，空间复杂度 $O(1)$。

impl Solution {
    pub fn length_of_longest_substring(s: String) -> i32 {
        use std::cmp::max;
        use std::collections::HashSet;
        let mut dict = HashSet::new();
        let s = s.as_bytes();
        let (mut ans, mut i) = (0, 0);
        for j in 0..s.len() {
            while dict.contains(&s[j]) {
                dict.remove(&s[i]);
                i += 1;
            }
            dict.insert(s[j]);
            ans = max(ans, (j - i + 1) as i32);
        }
        ans
    }
}