Length of the longest valid substring(Google Interview Questions)

 Question:

Length of the longest valid substring

Explanation:

A string consist of opening and closing parenthesis, so we need find the length of the longest valid parenthesis substring.

For Example:

                  str = ((()()()()

                   Result=8 

Program:

def findMaxLen(string):
    n = len(string)
    stack = []
    stack.append(-1)
    result = 0
    for i in range(n):
        if string[i] == '(':
            stack.append(i)
        else:
            if len(stack) != 0:
                stack.pop()
            if len(stack) != 0:
                result = max(result,
                             i - stack[len(stack) - 1])
            else:
                stack.append(i)
    return result

string = "((()()()()"
print(findMaxLen(string))
string = "()(()))))())))"
print(findMaxLen(string))