2 Around-the-corner puzzles

This is a rather interesting and relatively straight-forward type of puzzle, quite well-known among puzzle enthusiasts, yet I can't seem to find the proper name for it (It's called "Köşe Kapmaca" in Turkish). So I named it "Around-the-corner". The grey squares here are supposed to be circles originally, but I wanted to separate it from the Masyu puzzles, hence the grey squares.

Rules for Around-the-corner:
1. Draw a line that forms a (non-intersecting) loop and goes through every square.
2. At a grey square, the line turns 90 degrees.
3. From a grey square to another, there is exactly one 90 degree turn.