算法练习(3)-寻找最大的不重复子串

    /**
     * 查找最长不重复子串
     *
     * @param s
     * @return
     */

    public String getFirstLongestSubstring(String s) {
        System.out.println(s);
        char[] arr = s.toCharArray();
        Set<Character> set = new HashSet<>();
        int right = -1, maxLen = -1;
        String subStr = "";
        for (int i = 0; i < arr.length; i++) {
            if (i > 0) {
                //缩小左边界
                set.remove(arr[i - 1]);
            }
            while (right + 1 < arr.length && !set.contains(arr[right + 1])) {
                set.add(arr[right + 1]);
                //扩大右边界
                right++;
            }
            int len = right - i + 1;
            if (len > maxLen) {
                maxLen = len;
                char[] temp = new char[maxLen];
                s.getChars(i, right + 1, temp, 0);
                subStr = new String(temp);
            }
            if (maxLen >= arr.length - i) {
                break;
            }
        }
        return subStr;
    }