public static List<String> maxLength(String str) { if (str == null || str.length() == 0) { return new ArrayList<>(); } char[] arr = getManacherString(str); int[] pArr = new int[arr.length]; int center = -1; int right = -1; int max = Integer.MIN_VALUE; for (int i = 0; i < arr.length; i++) { pArr[i] = right > i ? Math.min(pArr[2 * center - i], right - i) : 1; while (i + pArr[i] < arr.length && i - pArr[i] > -1) { if (arr[i + pArr[i]] == arr[i - pArr[i]]) { pArr[i]++; }else { break; } } if (i + pArr[i] > right) { right = i + pArr[i]; center = i; } max = Math.max(max,pArr[i]); }