3 无重复字符的最长子串

3 无重复字符的最长字串

class Solution {
    public int lengthOfLongestSubstring(String s) {
        if (s == null)
            return 0;
        int left = 0;
        int right = -1;
        int maxLength = 0;
        Set<Character> set = new HashSet<Character>();
        for (left = 0; left < s.length(); left++) {
            if (left != 0) 
                set.remove(s.charAt(left- 1));
            while (right + 1 < s.length() && !set.contains(s.charAt(right + 1))) {
                set.add(s.charAt(right + 1));
                ++right;
            }
            maxLength = Math.max(maxLength, right - left + 1);
        }
        return maxLength;
    }
}