Fill factorial array so that we can find all factorial of r , n and n - r
fac = [ 0 for i in range ( n + 1 ) ] NEW_LINE fac [ 0 ] = 1 NEW_LINE for i in range ( 1 , n + 1 , 1 ) : NEW_LINE INDENT fac [ i ] = fac [ i - 1 ] * i % p NEW_LINE DEDENT return ( fac [ n ] * modInverse ( fac [ r ] , p ) % p * modInverse ( fac [ n - r ] , p ) % p ) % p NEW_LINE