[LeetCode] 3. 无重复字符的最长子串

public class L3 {
    public int lengthOfLongestSubstring(String s) {
        if(s.length()==0)return 0;
        HashMap<Character,Integer> map=new HashMap<>();
        int max=0;
        int left=0;
        for(int i=0;i<s.length();i++){
            if(map.containsKey(s.charAt(i))){
                left =Math.max(left,map.get(s.charAt(i))+1);
            }
            map.put(s.charAt(i),i);
            max=Math.max(max,(i-left+1));
        }
        return max;
    }
}