flotusocks

I recently accidentally pressed some combination of keys, and right now I'm
not sure what I pressed--but it basically took 2 different-sized windows and
put them right next to each other on the screen, of equal size and filling up
the entire screen. It's something I could theoretically achieve through
resizing the windows, but I was wondering if anyone knew what the exact
combination is that quickly does this (and perhaps any other similar
shortcuts that aren't mentioned in the Help guide).

Thanks!