## Roxar Interview Question

Software Engineer Interns**Country:**United States

**Interview Type:**Phone Interview

logic derivation:

Change of sign a element in set will return the target number.

Assume R is the resultant element and we will change the sign of R

So in the sum of the all elements of set (Say Sum), R is also included. First exclude that.

So we have sum of all elements except R => Sum – R.

Now, we changed sign of R and add it to get new sum of all elements.

( Sum –R ) + ( –R) = target //we changed sign of R

i.e, Sum –R –R = target

i.e, Sum – 2*R = target

Now for which i in set, this equation will satisfy, that is the result.

O(n) time, O(1) space

- ikoryf March 17, 2016