human
Find the number of valid parentheses expressions of given length | Returns value of Binomial Coefficient C ( n , k ).
Since C ( n , k ) = C ( n , n - k ).
Calculate value of [ n * ( n - 1 ) * -- - * ( n - k + 1 ) ] / [ k * ( k - 1 ) * -- - * 1 ].
A Binomial coefficient based function to find nth catalan number in O ( n ) time.
Calculate value of 2 nCn.
return 2 nCn / ( n + 1 ).
Function to find possible ways to put balanced parenthesis in an expression of length n.
If n is odd , not possible to create any valid parentheses.
Otherwise return n / 2 'th  Catalan Number.
Driver Code"
How can the above be solved in Python?
assistant
#Here is code to find the number of valid parentheses expressions of given length and the other steps required.
 def binomialCoeff ( n , k ) :
	res = 1 ;
	if ( k > n - k ) :
		k = n - k ;
	for i in range ( k ) :
		res *= ( n - i ) ;
		res /= ( i + 1 ) ;
	return int ( res ) ;
def catalan ( n ) :
	c = binomialCoeff ( 2 * n , n ) ;
	return int ( c / ( n + 1 ) ) ;
def findWays ( n ) :
	if ( n & 1 ) :
		return 0 ;
	return catalan ( int ( n / 2 ) ) ;
n = 6 ;
print ( " Total ▁ possible ▁ expressions ▁ of ▁ length " , n , " is " , findWays ( 6 ) ) ;