This question is about an algo change that happened ten days later. I don't think the 50% spike reported here on Oct 31 has anything to do with the Oct 22 algo change. It's probably some kind of traffic testing that Google did for xnavigator's domain.
Do i got any chance to reach the 31oct unique today?
It is possible, but not likely since it's been over a month. Whatever Google learned from that test was probably that the traffic they sent wasn't a good fit for your site.
An increase in uniqes is not a good thing on its own - that new traffic needs to be well-targeted to your site too.
To understand your 50% spike further, you should analyze your Google traffic from that day - what query phrases had they searched for, which pages on your site did Google send them to, and did they respond well (low bounce rate, high pages per unique).
Any site can enjoy (or suffer) ranking changes that are not triggered by an widepsread algorithm change. If we were inside Google, we might see that such changes are not "random", strictly speaking. But from the outside, any logic involved can be impossible to figure. That's why I appreciate the reports shared in the "Traffic Shaping" thread somuch.