Running advice

I've got a question about running. I'm preparing for my first BJJ tournament in about a month, for which I've been conditioning by lifting weights three times a week and running three times a week on alternate days, in addition to training hard at class in the evening 5 nights a week(and taking one day off each to let my body recover).

I was curious what my best bet is in regards to running and cardio. Should I be focusing on speed work by doing sprints or be doing longer distances at a strong pace (4+ miles) to build up my endurance? Perhaps a combination of the two? Or is running not even the best way for me to improve my cardio for this type of event?

I'm a little bit ignorant about proper exercise regimes, so any advice is appreciated.

ttt

i say do sets ( alternate between sprinting and jogging) but what do i know

I checked out the Taku's intervals and they seem to be exactly what I'm looking for. I even started on the routine today. Thanks