int num=999999; //or generally a very big number (like 10^6, etc.) int sum=0; for(int i=num; i>=1; i--) sum+=i;
So basically I want to find the sum of the
num + num-1 + num-2 +...+ 1, is there any way to make for loop faster or to get rid of it entirely?
This seems to be a math problem.
The loop can be avoided by using a formula for the sum of the integers from 1 up to and including a positive integer n, given as
sum = n * (n + 1) / 2