For C,C++--> Test ur C,C++ skills by Yashvanth kanithakar
For Java--> any good book.
12Q in General computer test?(Concentrate more on ceo's and founders of HP,Microsoft,intel,sap etc..)It even includes Q in OS,N/wing
12Q on C,
12Q on C++
12Q n java
All section r compulsory..(Even for Non java guys)
In the interview (ie on the 2nd ropund..they will ask Q mostly in C,C++,Java.The employee who r asking the Q r very jovial.So develop ur confidence level.They mostly ask abt ur latest projects,
If u clear this level..next will be HR round.
If u clear the second round mostly..u r selected(90%).
HR is just for a formality..