arts打卡第三周 – keep moving

class  {
    public String longestPalindrome(String s) {
        if (s == null || s.length() <= 1){
            return s;
        }
        char[] chars = s.toCharArray();
        Integer[] left = process(chars, true);
        Integer[] right = process(chars, false);
        if (left[1] - left[0] > right[1] - right[0]) {
            return s.substring(left[0], left[1]+1);
        } else {
            return s.substring(right[0], right[1]+1);
        }
    }

    private static Integer[] process(char[] chars, boolean left) {
        int min = 0;
        int max = 0;
        int len = 0;
        int index = chars.length / 2;
        while (index >= 0 && index <= chars.length - 1) {
            int l = 1;
            int p = index - 1;
            int q = index + 1;
            while (p >= 0 && chars[index] == chars[p]) {
                p--;
                l++;
            }
            while (q <= chars.length - 1 && chars[index] == chars[q]) {
                q++;
                l++;
            }
            while (p >= 0 && q <= chars.length - 1) {
                if (chars[p] != chars[q]) {
                    break;
                }
                p--;
                q++;
                l += 2;
            }
            if (l > len) {
                max = q - 1;
                min = p + 1;
                len = l;
            }
            index = left ? index - 1 : index + 1;
        }
        return new Integer[]{min, max};
    }
}