Hints: while loop

• Keep track of where you currently are (currentStreet, currentAve)
• Start at the startStreet, startAve
• Use a while loop.
• As long as you aren’t at the endpoint, keep going.
• Loop condition?
  • currentStreet != endStreet && currentAve != endAve?
  • currentStreet != endStreet || currentAve != endAve?
  • Test it out: (1, 1) -> (1, 3)?
  • Which one is still true?

Hints: Navigation

• Check if you can go east / west, north / south
  • Hint: \(x\) is even if \(x \% 2 == 0\).
• Nuance: can’t go east or west on 1 Street / 1 Ave
• Check if you want to go east / west, north / south
  • How do you know? (Draw this out.)

Simple Ideas

• Start with simple ideas
• If you want to go east and can, go east (as far as you need to)
• Otherwise, if you want to go west and can, go west
• Otherwise…
• What if you can’t go anywhere you want to go?
  • Simple idea that works: pick any direction you can go, and just go (1 block)
  • Program loops around and tries again.

Complicated Ideas?

• Get something that works first
• That may take you the entire week.
• If you have time, figure out how to optimize:
  • Test it out as much as possible
  • Find all the edge cases that your code doesn’t handle
  • Try to handle them
  • More if statements?
  • Elegant idea that solves all your problems? (Maybe not.)

Your Ideas?

What are some of the best ideas you all have had so far that seem to be working?

Presentation 1

• Weeks of 3/2 and 3/9: demo your project.
• Give a “big picture” explanation of the algorithm for how you solved the problem.
• Show / explain how your code implements that algorithm.
• Rubric / spreadsheet sign-up on BrightSpace.

Exercise

Write a method which takes in an integer array as a parameter, creates a new array that is twice as big, copies over all the elements of the old array and returns the new array.

public static int[] resizeArray(int[] originalArray) {
    // what goes in here?

}

Starter code.

Main method

Use it with the following main method:

int[] numbers = new int[5];
Scanner sc = new Scanner(System.in);
int index = 0;
System.out.println("Input in the first number: ");
while (sc.hasNextInt()) {
    int number = sc.nextInt();
    if (index >= numbers.length) {
        numbers = resizeArray(numbers);
    }
    numbers[index] = number;
    index++;
    System.out.println("Input in the next number: ");
}

ArrayList class

import java.util.ArrayList;
// must import the above!

// in main:
ArrayList<String> stringList = new ArrayList<>();
for(int i = 0; i < 100; i++) {
    stringList.add("hello!");
}
System.out.println(stringList.size());

ArrayList<Integer> integerList = new ArrayList<>();
for(int i = 0; i < 20; i++) {
    integerList.add(i * i);
}
System.out.println(integerList.get(15));

ArrayList class

• Built-in class that handles “resizeable arrays”
• Can use with any type!