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.

public int lengthOfLongestSubstring(String s) {
        if(null==s||"".equals(s)){
            return 0;
        }
        HashMap<Character,Integer> map = new HashMap<>();
        int re =0;
        int cur = 0;//当前子串的开始位置
        for(int i=0;i<s.length();i++){
            char c = s.charAt(i);
            if(map.containsKey(c)){
                re = (i-cur)>re?(i-cur):re;
                cur =map.get(c)>=cur?(map.get(c)+1):cur;
            }
            map.put(c,i);
        }
        return (s.length()-cur)>re?(s.length()-cur):re;
    }