I injured my knee a little over a month ago playing basketball and have been really slackin off on training even though i still try to do pushups and pullups and stuff at home.

Anyways, are there any good cardio type exercises that can be done at the gym or elsewhere that won't really put pressure on the knee?

Also is there any way to train the leg muscles without using the knee too much or should i stay away from that completely for another couple months or so? (i have a suspicion squatting very low the day before the injury might have weakened my knee in the first place but im not sure).