Recitation 4

1. Recitation 4 http://goo.gl/YN1BQ7 James Wei Professor Peck 1/31/2014

2. Big-Oh

3. Big-Oh

4. Common APT • Go to the course APT page and read the prompt for the Common APT. • In Eclipse, write code to solve this APT. Use the tester as always to verify that your solution works. • Feel free to work with a friend. • Ask the TAs if you have any questions!

5. Common APT • There are many different ways to solve this APT. • What are some different solutions for Common? • How do these different solutions perform (think Big O)?

6. List Manipulation • If you haven’t already, snarf the code for Recitation 4. • Run the code for “fruit1.txt” and take note of the output and what the code is doing. • Try running the code for “fruit2.txt”. • Why doesn’t this code work? Consider: • What do the words that fail to be removed have in common? • How is the iteration index changing with each iteration?

7. List Manipulation • Let’s fix the code. One way we can do that is by creating a new ArrayList and copying elements over into that new list. • Take some time to fix the code in Eclipse by writing a new method called removeFromListGood(). • This method should create a new ArrayList, copy over the elements we want to keep from the old list to the new one, then update the old list to be equal to the new list. • Consider: • How do we make sure we are creating a new list instead of a reference to the existing one? • How do we update the old list once we have finished making the new list?

8. List Manipulation • How else can we fix the broken list remove code? • We can try manipulating the index as we loop through the list. • Create a new method called removeFromListIndex() that does this. As you code, consider: • What is the index at the end of each iteration? • What should the index be at the end of each iteration? • When should the index be manipulated before the next iteration begins?

9. Have a good weekend! Don’t forget to submit your answers!