Task

The objective is to write a function that finds the sum of all positive multiples of 3 or 5 below n.

Show output for n = 1000.

This is is the same as Project Euler problem 1.

Extra credit: do this efficiently for n = 1e20 or higher.




 
def sum_multiples(d):
 ((./d) | floor) |  (d * . * (.+1))/2 ;
 
# Sum of multiples of a or b that are less than . (the input)
def task(a;b):
 . - 1
 | sum_multiples(a) + sum_multiples(b) - sum_multiples(a*b);