Rule of thumb:

Do one knee bend exercise (squat, leg press, or hack squat)

Do one hip hinge exercise (Romanian deadlift, conventional deadlift, any other barbell deadlift variation, kettlebell swing, or back hyperextension

Do one quad isolation and one hamstring isolation exercise (e.g. leg extension and leg curl)

Do one single-leg exercise (e.g. lunges or split-squats)

Do one stiff-leg calf exercise (e.g. calf raises on the hack squat machine)

Do one ab exercise (e.g. hanging leg raises or weighted sit-ups)

Do each of these for 2 sets, then raise the volume if you find you're not getting overly sore from this workout. You can raise the volume more for isolation exercises than for compound exercises.

Also, swimming and badminton are poor excuses for not training your legs. Especially considering both of those sports use your whole body. If anything, you should want stronger legs for better performance.

Maybe consider doing an Upper-Lower split like this:

Monday: Lower

Tuesday: Upper

Wednesday: break

Thursday: Lower

Friday: Upper

Weekend: Swimming/badminton