leetcode 3 longest sustring.py

# Best
def lengthOfLongestSubstring(self, s: str) -> int:
        l = 0
        r = 0
        occ = {}
        mx = 0
        while r < len(s):
            if s[r] not in occ:
                occ[s[r]] = 1
                r += 1
                mx = r - l if r - l > mx else mx
            elif occ[s[r]] == 0:
                occ[s[r]] = occ[s[r]] + 1
                r += 1
                mx = r - l if r - l > mx else mx
            elif occ[s[r]] > 0:
                occ[s[l]] = occ[s[l]] - 1
                l += 1
        return mx
        
def lengthOfLongestSubstring(self, s: str) -> int:
        left, right = 0, 0
        answer = [left, right]  # the window
        diff = 0
        hashset = defaultdict(int)  # this will set 0 as default value to the key, if that key is not present
        for i in s:
            if hashset[i] == 0:  # move the right pointer to the right, if there is no repetation
                hashset[i] += 1
                right += 1
            else:
                while hashset[i] >=1:  # constrict the left pointer
                    hashset[s[left]] -= 1
                    left += 1
                hashset[i] += 1  # update the current substring
                right += 1
            
            if right - left > diff:  # update the window with longest substring
                diff = right - left
                answer[0], answer[1] = left, right
        
        return answer[1] - answer[0]