Free Response - Climbing Club C

The following is part c of a free response question from 2012. It was question 1 on the exam. You can see all the free response questions from past exams at https://apstudents.collegeboard.org/courses/ap-computer-science-a/free-response-questions-by-year.

Question 1. A mountain climbing club maintains a record of the climbs that its members have made. Information about a climb includes the name of the mountain peak and the amount of time it took to reach the top. The information is contained in the ClimbInfo class as declared below.

public class ClimbInfo
{
   /** Creates a ClimbInfo object with name peakName and time climbTime.
     * @param peakName the name of the mountain peak
     * @param climbTime the number of minutes taken to complete the climb
     */
   public ClimbInfo(String peakName, int climbTime)
   { /* implementation not shown */ }

   /** @return the name of the mountain peak*/
   public String getName()
   { /* implementation not shown */ }

   /** @return the number of minutes taken to complete the climb*/
   public int getTime()
   { /* implementation not shown */ }

   // There may be instance variables, constructors, and methods
   // that are not shown.
}

The ClimbingClub class maintains a list of the climbs made by members of the club. The declaration of the ClimbingClub class is shown below. You will write two different implementations of the addClimb method. You will also answer two questions about an implementation of the distinctPeakNames method

public class ClimbingClub
{
   /** The list of climbs completed by members of the club.
    * Guaranteed not to be null. Contains only non-null
    * references.
    */
   private List<ClimbInfo> climbList;

   /** Creates a new ClimbingClub object. */
   public ClimbingClub()
   {
      climbList = new ArrayList<ClimbInfo>();
   }

   /** Adds a new climb with name peakName and time climbTime
    * to the list of climbs.
    * @param peakName the name of the mountain peak climbed
    * @param climbTime the number of minutes taken to complete
    * the climb
    */
   public void addClimb(String peakName, int climbTime)
   {
      /* to be implemented in part (a) */
   }

   /** @return the number of distinct names in the list of climbs */
   public int distinctPeakNames()
   {
      /* implementation shown in part (c) */
   }

   // There may be instance variables, constructors, and methods
   // that are not shown.
}

Part c. The ClimbingClub method distinctPeakNames is intended to return the number of different names in climbList. For example, after the following code segment has completed execution, the value of the variable numNames would be 3.

ClimbingClub hikerClub = new ClimbingClub();
hikerClub.addClimb("Monadnock", 274);
hikerClub.addClimb("Whiteface", 301);
hikerClub.addClimb("Algonquin", 225);
hikerClub.addClimb("Monadnock", 344);

Consider the following implementation of method distinctPeakNames.

/** @return the number of distinct names in the list of climbs */
public int distinctPeakNames()
{
   if (climbList.size() == 0)
   {
      return 0;
   }

   ClimbInfo currInfo = climbList.get(0);
   String prevName = currInfo.getName();
   String currName = null;
   int numNames = 1;
   for (int k = 1; k < climbList.size(); k++)
   {
      currInfo = climbList.get(k);
      currName = currInfo.getName();
      if (prevName.compareTo(currName) != 0)
      {
         numNames++;
         prevName = currName;
      }
   }
  return numNames;
}

8-9-1: Does this implementation of the distinctPeakNames method work as intended when the addClimb method stores the ClimbInfo objects in the order they were added as described in part (a)?

• yes
• Did you trace it to see what it would do?
• no
• This code depends on the peakNames being in alphabetical order by peakName.

8-9-2: Does this implementation of the distinctPeakNames method work as intended when the addClimb method stores the ClimbInfo objects in alphabetical order by name as described in part (b)?

• yes
• This code depends on the peakNames being in alphabetical order by peakName.
• no
• Did you trace it to see what it would do?

Try it Out

import java.util.List; import java.util.ArrayList; class ClimbInfo { private String name; private int time; /** Creates a ClimbInfo object with name peakName and time climbTime. * * @param peakName the name of the mountain peak * @param climbTime the number of minutes taken to complete the climb */ public ClimbInfo(String peakName, int climbTime) { name = peakName; time = climbTime; } /** @return the name of the mountain peak */ public String getName() { return name; } /** @return the number of minutes taken to complete the climb */ public int getTime() { return time; } public String toString() { return "Peak name: " + name + " time: " + time; } } public class ClimbingClub { /** The list of climbs completed by members of the club. * Guaranteed not to be null. Contains only non-null references. */ private List<ClimbInfo> climbList; /** Creates a new ClimbingClub object. */ public ClimbingClub() { climbList = new ArrayList<ClimbInfo>(); } /** Adds a new climb with name peakName and time climbTime to the end of the list of climbs * * @param peakName the name of the mountain peak climbed * @param climbTime the number of minutes taken to complete the climb */ public void addClimbA(String peakName, int climbTime) { climbList.add(new ClimbInfo(peakName, climbTime)); } /** Adds a new climb with name peakName and time climbTime to the list of climbs in order by name * * @param peakName the name of the mountain peak climbed * @param climbTime the number of minutes taken to complete the climb */ public void addClimbB(String peakName, int climbTime) { // find the position for the new item int index = 0; while (index < climbList.size() && climbList.get(index).getName().compareTo(peakName) <= 0) { index++; } climbList.add(index, new ClimbInfo(peakName, climbTime)); } /** @return the number of distinct names in the list of climbs */ public int distinctPeakNames() { if (climbList.size() == 0) { return 0; } ClimbInfo currInfo = climbList.get(0); String prevName = currInfo.getName(); String currName = null; int numNames = 1; for (int k = 1; k < climbList.size(); k++) { currInfo = climbList.get(k); currName = currInfo.getName(); if (prevName.compareTo(currName) != 0) { numNames++; prevName = currName; } } return numNames; } public String toString() { String output =""; for (ClimbInfo info : climbList) { output = output + info.toString() + "\n"; } return output; } public static void main(String[] args) { ClimbingClub hikerClub = new ClimbingClub(); hikerClub.addClimbA("Monadnock", 274); hikerClub.addClimbA("Whiteface", 301); hikerClub.addClimbA("Algonquin", 225); hikerClub.addClimbA("Monadnock", 344); System.out.print(hikerClub); System.out.println("The order printed above should be Monadnock, Whiteface, Algonquin, Monadnock"); System.out.println("Distinct peaks is " + hikerClub.distinctPeakNames() + " and should be " + 3); hikerClub = new ClimbingClub(); hikerClub.addClimbB("Monadnock", 274); hikerClub.addClimbB("Whiteface", 301); hikerClub.addClimbB("Algonquin", 225); hikerClub.addClimbB("Monadnock", 344); System.out.print(hikerClub); System.out.println("The order printed above should be Algonquin, Monadnock, Monadnock, Whiteface"); System.out.println("Distinct peaks is " + hikerClub.distinctPeakNames() + " and should be " + 3); } }

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