CS241: Spring 2015 -- Lecture 16, selectionSort and DynamicProgramming

1. What goes in an abstract class?
   1. Common variables - variables every subclass need
   2. Common methods - methods every subclass needs
   3. Abstract methods - methods every subclass must implement (since they are different in different subclasses)
   4. Constructors - if more than one subclass will do the same thing in constructors
2. A lovely bug in selection sort (on testing, debugging, and following advice!)

       iterate n-1 times (i ranging from 0 to n-1) {
           swap ith and indexOfSmallest from i to n-1
           }
       }

   In more detail:

       iterate n-1 times (for i=0 to n-1) {
           indexOfSmallest = findSmallestFromIthDown(i)
           swap ith and indexOfSmallest from i to n-1
           }
       }
                   
       int findSmallestFromIthDown(int i) {
           ...
       }            
           

3. Counting operations.
   1. bubble sort
   2. selection sort
   3. insertion sort
4. You can trade space for time (and vice-versa). E.g. calculating Fibonacci numbers.