• Be sure to read the "Individual Work" section of your green sheet. You may not copy your work from another student. You may not collaborate with other students, except on Piazza. When code is posted on Piazza, it is usually far from perfect and should not be copied without improving it. If you do copy from Piazza, you MUST provide attribution. Use the format

  // https://piazza.com/class#fall2012/cs46a/911

Part A. Write the following methods in a class Arrays1.

• public boolean isUpThenDown(int[] values)

  Returns true if the array is strictly increasing up to an index, then strictly decreasing from that index to the end

• public int upsAndDowns(int[] values)

  Returns the number of strictly increasing and strictly decreasing segments in the array.

Draft: Implement the isUpThenDown method.

netbrat draft | final

Part B. In the Arrays2 class, add methods

• public int[] copyWithNegativesFirst(int[] values)

  Returns a new array with the same values in which the negative numbers come before the nonnegative numbers, without otherwise changing the order

• public void negativesFirst(int[] values)

  Reorders the elements in values so that the negative numbers come before the nonnegative numbers, without otherwise changing the order. You must do this in-place. You may not allocate another array, call another method, put the numbers in a string, etc. You may only declare ≤ 4 variables.

  A loop index for (int i = 0...) counts as a variable!

• public void negativesFirst(ArrayList<Integer> values)

  As before, but now you may only declare 2 variables.

Draft: Just implement copyWithNegativesFirst.

netbrat draft | final

Part C. It is a well-known fact that in a men's restroom most people will choose the middle of the longest empty subsequence of stalls. If there is more than one such position, the one closest to the door is chosen. Implement a class MensRoom with these methods:

• public MensRoom(int totalNumberOfStalls)
• public String toString()

  Returns a string where an empty stall is an underscore _ and a nonempty stall is an uppercase X.

• public int add()

  Adds an occupant with the choice described above, where the door is assumed next to index 0, and returns the index of the stall. If the restroom is fully occupied, returns -1.

• public boolean remove(int i)

  Removes the person at stall i. Returns true if the removal was successful (i was a valid index and there was an occupant), false otherwise.

Draft: The constructor, toString, and add for one person.

netbrat draft | final