CS211 Prelim 2, Spring 2006
Grading Guide

Problem 1:
  -4 points for each problem

  Common mistakes:
  -Strings aren't mutable!
  -definition of non-terminal

Problem 2:
  Part a:
  -2 If solution incorrect.
  -1 If did not specify observer.

  Part b:
  -2 For each incorrect argument.
  -2 If a pair of arguments is swapped.

  Part c:
  -2 If variables are shadowed, but not initialized in the Annulus.
  -2 If not specified what methods should be overridden.
  -2 Incorrect variable initialization / no appropriate definitions. 
  -2 Inner radius not initialized in constructor.
  -6 No area method.
  -1 If rewrote code from super.area().

  Common mistakes:
  1) Shadowing fields of the super class and then not initializing them.
  2) Making two calls to the super constructor and expecting it to return a
     value.

Problem 3:
  
  Part a: 5 points
  3 pts max if height is not true
  4 points max if root is not 2
  no points if not a BST
  
  Part b: all or nothing

  Part c: 
  Base case: 3 points; 
     2 points max if h=1, not 0
  Inductive hypothesis: 3 points; 
     0 points if not strong induction on height of tree
  Inductive case: 10 points
     -2 for not stating that all elements of the tree are present after
        the call to swap()
     -8 points for proof

Problem 4: 

  Part a: 6 points
  -1 if identify problem as void remove(int x) (correct answer is void remove(Object x))
  if correct problem identified,
   -3 if no statement about the problem
   -2 if no specification (the comment)

  Part b: 6 points
  -4 if identify a legitimate problem about add (add is not an observer)
  if correct problem identified,
   -3 if no statement about the problem
   -2 if specification (the comment)

  Part c: 6 points
  -2 for "small problem"
  -4 for "big problem"
  -6 "completely wrong"

  Part d:
  -7 if answered "no"
  -(2 to 4) for problems in the code