3. Longest Substring Without Repeating Characters

METHOD 1
class Solution:
    def numSubseq(self, nums: List[int], target: int) -> int:
        nums.sort()
        n=len(nums)
        l,r=0,n-1
        while l<r:
            if nums[l]+nums[r]<tar:
                ans=ans+(r-l+1)+

class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        vis=[False]*256
        l,r,res=0,0,0
        for r in range(len(s)):
            while vis[ord(s[r])]==True:
                vis[ord(s[l])]=False
                l+=1
            res=max(res,r-l+1)
            vis[ord(s[r])]=True
        return res