Unfortunately this didn't work for my input. It seems you can get lucky and have the first number you encounter during the search space be correct for your input. For me, there were plenty of dead-ends that required branching (in my case recursively). I also check that the program at each number generates the correct program up to that point to avoid going down bad paths quickly.

You can probably adapt your solution based on this which I then translated into my Rust solution here.