I give class 12 board in 2017 in which i failed in computer science which is my six subject and now i want choose computer science engg
You will not face any problems at the time of placements as you are pass in class 12th board exams in 5 subjects And that's what the companies look at.You need not to worry about that from now.
Just concentrate on engineering entrance exams preparations and give maximum mock tests and solve previous years question papers.
Good luck.

Good luck!
Look, knowledge is everything & if you are going for IT sectors so they will not check what have you done, they should search what you can do for them..
But sometime i think company may ask me you failed in computer science in class 12th.It means you are failer then why we choose failer there are many there students who pass computer science or may not opt computer science in class 12th
Anyway,thank you sir for frequently answering my question.