missing integers task.txt

You are given a very very large list of unsorted integers. These
  integers are supposed to be unique and, if sorted, contiguous. However, you
  suspect that this is not the case, so you want to write code to check for
  missing or duplicate integers. Write code to return these results:
  
   - Are there any missing or duplicate integers?
   - How many missing integers?
   - How many duplicate integers?
   - Which integers are missing?
   - Which integers are duplicates, and how many duplicates of each
  integer?
  
   You may write separate code or functions to answer each of these
   questions;
   i.e. it's ok to pass over the data more than once to answer all
   questions.
   Your implementation may be in any language/system. However,
   remember that this is big data, so the solution needs to useable at that scale.
  
   Please spend no more than 3 hours. If you'd like to spend more, it's up
   to you - just make a note of when you get to three and report back
   as to when you restarted the clock .