3. The longest string without repetition (lengthOfLongestSubstring)

3. The longest string without repetition (lengthOfLongestSubstring)

1. python

class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        if not s:
            return 0
        cur_len,max_len=0,0
        s_len = len(s)
        left = 0
        hashSet = set()
        for i in range(s_len):
            cur_len+=1
            while s[i] in hashSet:  
                hashSet.remove(s[left]) 
                left+=1
                cur_len-=1
            if cur_len>max_len:
                max_len = cur_len
            hashSet.add(s[i])
        return max_len

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2. Java

class Solution {
    
    
    public int lengthOfLongestSubstring(String s) {
    
    
        Set<Character> hashSet = new HashSet<Character>();
        int cur=0;
        int max=0;
        int left=0;
        for(int i=0;i<s.length();i++){
    
    
            ++cur;
            while(hashSet.contains(s.charAt(i))){
    
    
                hashSet.remove(s.charAt(left));
                left++;
                cur--;
            }
            if(cur>max){
    
    
                max=cur;
            }
            hashSet.add(s.charAt(i));
        }
        return max;
    }
}

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