LeetCode [3] Longest Substring Without Repeating Characters

Given a string, find the length of the longest substring without repeating characters.

Example 1:

Input: "abcabcbb"
Output: 3 
Explanation: The answer is "abc", with the length of 3. 

Example 2:

Input: "bbbbb"
Output: 1
Explanation: The answer is "b", with the length of 1.

Example 3:

Input: "pwwkew"
Output: 3
Explanation: The answer is "wke", with the length of 3. 
             Note that the answer must be a substring, "pwke" is a subsequence and not a substring.

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class Solution { public: int lengthOfLongestSubstring(string s) { int ret = 0, n = s.size(), l = 0, r = 0; map<char, int> mp; while(r<n){ while(mp[s[r]]>0){ mp[s[l]]--; l++; } mp[s[r]]++; if(ret<r-l+1) ret = r-l+1; r++; } return ret; } };

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class Solution { public int lengthOfLongestSubstring(String s) { int l = 0, r = 0, n = s.length(); int ret = 0; Set<Character> set = new HashSet<>(); while(l<=r && r<n) { if(set.contains(s.charAt(r))) { set.remove(s.charAt(l++)); } else { ret = Math.max(ret, r-l+1); set.add(s.charAt(r++)); } } return ret; } }