package stack_and_queue;

import java.util.Stack;

// Length of the longest valid substring

public class P18 {

public static int findMaxLen(String s) {

Stack<Character> st = new Stack<>();

Stack<Integer> index = new Stack<>();

int length, max = 0;

index.push(-1);

for(int i = 0; i < s.length(); i++) {

if(s.charAt(i) == '(') {

st.push(s.charAt(i));

index.push(i);

}

else {

if(!st.isEmpty()) {

st.pop();

index.pop();

length = i - index.peek();

if(max < length)

max = length;

}

index.push(i);

}

}

return max;

}

public static void main(String[] args) {

}

}