0.3 滑动窗口

[3. 无重复字符的最长子串](https://leetcode.cn/problems/longest-substring-without-repeating-characters/?envType=study-plan-v2&envId=top-100-liked)
```py
class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        win = set()
        left = 0
        ans = 0
        for right, item in enumerate(s):
            while item in win:
                win.remove(s[left])
                left += 1
            win.add(item)
            ans = max(ans, right - left + 1)
        return ans
```
[438. 找到字符串中所有字母异位词](https://leetcode.cn/problems/find-all-anagrams-in-a-string/?envType=study-plan-v2&envId=top-100-liked)
```py
class Solution:
    def findAnagrams(self, s: str, p: str) -> List[int]:
        needs = {}
        for c in p:
            needs[c] = needs.get(c, 0) + 1
        window = {}
        left = right = 0
        m, n = len(s), len(p)
        ans = []
        while right < m:
            c = s[right]
            if c not in needs:
                window.clear()
                left = right = right + 1
            else:
                window[c] = window.get(c,0) + 1
                if right - left + 1 == n:
                    if window == needs:
                        ans.append(left)
                    window[s[left]] -= 1
                    left += 1
                right += 1
        return ans
```