Self-Evaluation for CS251 Students

25 pts

1. Write a non-recursive member function of a linked list type that deletes every negative number from a linked list. If the linked list has no negative numbers it should do nothing. If a list has 2,-3, 42,-8,-9, 11,-38, 4,-2,-13 the member would change it to: 2, 42,11,4 (do not use other member functions).

25 pts

2. If the ListOfInts, lisa, is –2, 3, 1,-5, 7, 4, 7 then what is
lisa.recurse()? lisa.rest.recurse()?

public class ListOfInts
{
boolean emptyList = true; // true if list is empty
int firstData; // first data item in list if not empty
ListOfInts rest; // rest of the list if not empty
/** is list empty? */
public boolean empty() { returnt emptyList; }
/** what is first element of list */
public int first() { if(empty()) throw new Exception(); return firstData; }
/** puts a new item at beginning of list */
public void push(int newFirst)
{ ListOfInts newRest = new ListOfInts();
newRest.emptyList = emptyList;
newRest.firstData = firstData;
newRest.rest = rest;
rest = newRest;
emptyList = false;
firstData = newFirst;
} // end push
… // more methods go here but not necessary for review
/** method to test understanding of recursion in lists */
public int recurse()
{
if(rest.empty()) return first();
else if(first()<0)
return first()+2*rest.Recurse();
else return first() + rest.Recurse();
} // end recurse
} // end ListOfInts

25 pts

3. Present the items of this tree in prefix, postfix and infix: