balanced parentheses created by vetional - https://repl.it/@vetional/balanced-parentheses

balanced parentheses.py

# Print all possible n pairs of balanced parentheses.
# For example, when n is 2, the function should print “(())” and “()()”. 
# When n is 3, we should get “((()))”, “(()())”, “(())()”, “()(())”, “()()()”.

def fn(l,r):
  #print ('call : fn(' +  str(l) + ',' + str(r) + ')')
  if l < 0 or r < 0 or l > r:
    return 0
  if l == 0 and r == 0:
    return 1
  if l < r:
    #print ('doing : fn(' +  str(l-1) + ',' + str(r) + ') + fn(' + str(l) + ','  + str(r-1) + ')')
    ways = fn(l-1,r) + fn(l,r-1)
  else:
    #print ('doing : fn(' +  str(l-1) + ',' + str(r) + ')')
    ways = fn(l-1, r)
  return ways
  
print (fn(5,5))