State the reason for not using a binary search.

Construct an algorithm in pseudocode for the method isIn(X, COL).

Construct an algorithm in pseudocode that will output the number of students who have chosen both tennis and football. The method isIn() should be used in your answer.

The school coordinator would like to check whether there are students who have not yet chosen any one of the three sports.

Construct an algorithm in pseudocode that will output the names of students who have not yet chosen any one of the three sports. An appropriate message should be displayed if every student has chosen a sport.

Award [1 max].

Because the array SNAMES is not sorted/ordered;

Award [4 max].
Award [1] for initializing and returning/outputting flag;
Award [1] for a while loop;
Award [1] for correct comparison and updating flag;
Award [1] for the correct use of collection methods (resetNext(), hasNext() and getNext());

Example 1:

isIn(X,COL)
   PRESENT=False
   COL.resetNext()
   loop while COL.hasNext()and not PRESENT
     Y= COL.getNext()
      if X== Y
         then PRESENT=True
      end if
   end loop
   return PRESENT
end isIn

Example 2:

isIn(X,COL)
   P=0
   COL.resetNext()
   loop while COL.hasNext()
      if X== COL.getNext()
         then P=1
      end if
   end loop
   if P==1                              // NOTE: instead of if statement only
     then return True                   // the statement : return P==1
     else return False                  // may be written
   end if
end isIn

Award [3 max].
Award [1] for initializing, updating and returning/outputting COUNT;
Award [1] for a while loop;
Award [1] for calling method isIn();
Award [1] for correct use of collection methods (resetNext(), hasNext() and getNext();

Example 1 (loop through collection FOOTBALL):

COUNT=0
FOOTBALL.resetNext()
loop while FOOTBALL.hasNext()
   X== FOOTBALL.getNext()
   if isIn(X,TENNIS)
      then COUNT=COUNT+1
   end if
end loop
output COUNT

Example 2 (loop through collection TENNIS):

COUNT=0
TENNIS.resetNext()
loop while TENNIS.hasNext()
   if isIn(TENNIS.getNext(),FOOTBALL)
      then COUNT=COUNT+1
   end if
end loop
output COUNT

Award [7 max].

Award [1] for the use of flag;
Award [1] for looping through the array SID;
Award [2] for correct use of logical operators not/and/or in if statement, 1 mark for minor error;
Award [1] for the correct call of method isIn();
Award [1] for outputting the name from the array SNAMES within the loop;
Award [1] for outputting message(if needed) after the loop;

Example 1:

FLAG=True
loop for K=0 to 99
  if not( isIn(SID[K],FOOTBALL)or isIn(SID[K],BASKETBALL) or isIn(SID[K],TENNIS))
     then
       output SNAME[K]
       FLAG=False
   end if
end loop
if FLAG
   output 'Each of the students is on at least one of the three teams'
end if

Note: the condition in if statement could be written as
not(isIn(SID[K],FOOTBALL))and not(isIn(SID[K],BASKETBALL))and not(isIn(SID[K],TENNIS))

Example 2:

Award [1] for the use of flag
Award [1] for looping through the array SID
Award [1] for nested if statements
Award [1] for correct logical expressions in each of these ifs
Award [1] for the correct call of method isIn()
Award [1] for outputting the name from the array SNAMES within the loop
Award [1] for outputting message(if needed) after the loop

X=1
loop for K=0 to 99
   if not(isIn(SID[K],FOOTBALL))
     then if not (isIn(SID[K],BASKETBALL))
          then if not(isIn(SID[K],TENNIS))
                then
                 output SNAME[K]
                 X=0
               end if
          end if
   end if
end loop
if X==1
   output 'Every student has chosen a sport'
end if

Most candidates recognised that a binary search would only work with sorted data.

Candidates were required to produce an algorithm for the method described in the question. Most candidates achieved some marks for this algorithm, but full marks were rare. The scenario involved the use of a collection, so collection methods were expected within the algorithm. Many candidates failed to demonstrate the use of collection methods.

Candidates were required to construct a second algorithm involving the use of the method defined in part b. As with part b, the use of collection methods was also expected, but was often missing. Candidates who attempted the question, however, generally achieved some marks.

A final algorithm was required based on the question scenario. Some candidates did not attempt this question. A small number of candidates achieved high marks by demonstrating good programming skills. However, a large number of candidates scored low marks for the construction of a partial solution or a solution that was partially correct.