package DynamicProgramming;

import java.util.Scanner;

/**
 * Given a string containing just the characters '(' and ')', find the length of the longest valid
 * (well-formed) parentheses substring.
 *
 * @author Libin Yang (https://github.com/yanglbme)
 * @since 2018年10月5日
 */
public class LongestValidParentheses {

 public static int getLongestValidParentheses(String s) {
 if (s == null || s.length() < 2) {
 return 0;
 }
 char[] chars = s.toCharArray();
 int n = chars.length;
 int[] res = new int[n];
 res[0] = 0;
 res[1] = chars[1] == ')' && chars[0] == '(' ? 2 : 0;

 int max = res[1];

 for (int i = 2; i < n; ++i) {
 if (chars[i] == ')') {
 if (chars[i - 1] == '(') {
 res[i] = res[i - 2] + 2;
 } else {
 int index = i - res[i - 1] - 1;
 if (index >= 0 && chars[index] == '(') {
 // ()(())
 res[i] = res[i - 1] + 2 + (index - 1 >= 0 ? res[index - 1] : 0);
 }
 }
 }
 max = Math.max(max, res[i]);
 }

 return max;
 }

 public static void main(String[] args) {
 Scanner sc = new Scanner(System.in);

 while (true) {
 String str = sc.nextLine();
 if ("quit".equals(str)) {
 break;
 }
 int len = getLongestValidParentheses(str);
 System.out.println(len);
 }

 sc.close();
 }
}