get_longest_run brackets python

# Python program to find length of the longest valid 
# substring 
  
def findMaxLen(string): 
    n = len(string) 
  
    # Create a stack and push -1 as initial index to it. 
    stk = [] 
    stk.append(-1) 
  
    # Initialize result 
    result = 0
  
    # Traverse all characters of given string 
    for i in xrange(n): 
      
        # If opening bracket, push index of it 
        if string[i] == '(': 
            stk.append(i) 
  
        else:    # If closing bracket, i.e., str[i] = ')' 
      
            # Pop the previous opening bracket's index 
            stk.pop() 
      
            # Check if this length formed with base of 
            # current valid substring is more than max  
            # so far 
            if len(stk) != 0: 
                result = max(result, i - stk[len(stk)-1]) 
  
            # If stack is empty. push current index as  
            # base for next valid substring (if any) 
            else: 
                stk.append(i) 
  
    return result 
  
# Driver program 
string = "((()()"
print findMaxLen(string) 
  
string = "()(()))))"
print findMaxLen(string) 
  
# This code is contributed by Bhavya Jain