# Talk:TADM2E 4.6

From Algorithm Wiki

What about this approach?

- Create a hash entry for every value from S1[i].
- For each value in S2 look for a hash hit on x-S2[i].

Isn't that an O(n) solution?

According to the formal definition, an O(n) solution is also an O(n log n) solution, is it not?