String Longest Valid Parentheses

19 Jun 2019

public int longestValidParentheses(String s) {
	int left = 0, right = 0, maxlength = 0;
	for (int i = 0; i < s.length(); i++) {
		if (s.charAt(i) == '(') {
			left++;
		} else {
			right++;
		}
		if (left == right) {
			maxlength = Math.max(maxlength, 2 * right);
		} else if (right >= left) {
			left = right = 0;
		}
	}
	left = right = 0;
	for (int i = s.length() - 1; i >= 0; i--) {
		if (s.charAt(i) == '(') {
			left++;
		} else {
			right++;
		}
		if (left == right) {
			maxlength = Math.max(maxlength, 2 * left);
		} else if (left >= right) {
			left = right = 0;
		}
	}
	return maxlength;
}