Since Your  rank is very Good to get into top engineering colleges through comedk

but still if you demand only of CSE it will  be very  difficult as to make up in to top three colleges with CSE require rank below 400

Last year cut off for CSE branch are:

BMS 373

MS RAMIAH 451

RV 180

BIT( Bangalore institute of technology) 1484

P E S institute of technology 1063

And PESIT but now it's a university so no seat through comedk

Also i would suggest you try out other colleges bcoz CSE in above mentioned rank is very rare .