leetcode-3 无重复字符的最长子串

题目描述：给定一个字符串 s ，请你找出其中不含有重复字符的 最长子串 的长度。

代码实现

class Solution {
    public int lengthOfLongestSubstring(String s) {
        Map<Character, Integer> need = new HashMap<>();

        int left = 0, right = 0, start = 0, len = 0;
        while (right < s.length()) {
            char c = s.charAt(right);
            right++;
            need.merge(c, 1, (oldVal, newVal) -> ++oldVal);
            while (need.get(c).equals(2)) {
                if (right - 1 - left > len) {
                    start = left;
                    len = right - 1 - left;
                }
                char l = s.charAt(left);
                left++;
                need.compute(l, (k, v) -> --v);
            }
        }
        return right - left > len ? right - left : len;
    }
}