human
Sum of all subsequences of length K | Function to find nCr.
Function that returns factorial of n.
Function for finding sum of all K length subsequences.
Calculate the sum of array.
Calculate nCk.
Return the final result.
Driver Code"
Solution in Python:
 Can you provide a code to sum of all subsequences of length K and the other steps required?
assistant
#Here is code to sum of all subsequences of length K and the other steps required.
 def nCr ( n , r ) :
	return fact ( n ) / ( fact ( r ) * fact ( n - r ) )
def fact ( n ) :
	res = 1
	for i in range ( 2 , n + 1 ) :
		res = res * i
	return res
def sumSubsequences ( arr , n , k ) :
	sum = 0
	for i in range ( 0 , n ) :
		sum = sum + arr [ i ]
	kLengthSubSequence = nCr ( n , k )
	ans = sum * ( ( k * kLengthSubSequence ) / n ) ;
	return ans
arr = [ 7 , 8 , 9 , 2 ]
k = 2
n = len ( arr )
print ( sumSubsequences ( arr , n , k ) )