I'm not totally sure about "zigzag". Is it literally L?R, then down, then L/R etc?
If so, I have some problems:
I've got the two solutions for 31 ( as well as 30), so they must both go right, then down. One must eventually go through Square 42, but neither of them fit.
The solutions for 45,46 are suspiciously similar, but presumably aren't superimposed. Putting them in gives me trouble with 37 - help, please.