Hello, Which one is grammatically correct?I have resorted to as many solutions as they exist.I have resorted to as many solutions as it exists.I mean: every possible solution

I have resorted to as many solutions that exist.

In English, I think the most common way of saying this would be "I have resorted to all possible solutions."
(I personally would say all known solutions, or even all of which I am familiar, depending on how likely I am to know all that exist.)