CSCI 3300: Exercises for quiz 6

CSCI 3300
Spring 2009
Exercises for Quiz 6

These questions use the following type Cell.

    struct Cell
    {
      Cell* next;
      int item;

      Cell(int i, Cell* n)
      {
        item = i;
        next = n;
      }
    };

Write a statement that will create variable L, of type Cell*, and make it point to new linked list holding only one value, 30.

Answer
Which of the following will create variable L and make it point to a new linked list holding 1 and 2, in that order?
1. Cell* L = new Cell*(1, new Cell*(2, NULL));
2. Cell* L = new Cell*(2, new Cell*(1, NULL));
3. Cell* L = new Cell(1, new Cell(2, NULL));
4. Cell* L = new Cell(2, new Cell(1, NULL));
5. Cell* L = new Cell(new Cell(1, 2, NULL));
Answer
Suppose that L is a variable of type Cell* that has already been created and t is a variable of type int. Linked list L has at least two numbers in it. Which of the following sets variable t to the second integer in list L?
1. t = L.item.next;
2. t = L.next.item;
3. t = L[2];
4. t = L->item->next;
5. t = L->next->item;
Answer
Which of the following sequences of statements correctly removes the first cell of a linked list L, making L point to the rest of the list, and deletes the removed cell?
1. Cell* t = L; L = L->next; delete L;
2. Cell* t = L; L = L->next; delete t;
3. Cell* t = L->next; L->next = L; delete t;
4. Cell* t = L; delete t; L = L->next;
5. Cell* t = L; L->next = L; delete t;
Answer
Write a C++ definition of function addToFront(x,L) which returns the list that you get by adding number x to the front of list L.
```
Cell* addToFront(int x, Cell* L)
```
Answer
Write a C++ definition of function isSingleton(L) that returns true if L is a singleton list, and false otherwise. (A singleton list has exactly one number in it.)
```
bool isSingleton(const Cell* L)
```
Answer
Write a C++ definition of function firstPositive(L) that returns the first positive number in linked list L. If L does not contain a positive number, then firstPositive(L) should return 0. Remember that L is a linked list, not an array.
```
int firstPositive(const Cell* L)
```
Answer
Write a C++ definition of function isSorted(L), which returns true if L is in strictly ascending order and returns false if L is not in ascending order. The empty list is considered to be in ascending order.
```
  bool isSorted(const Cell* L)
```
Answer
Explain why the following is not a correct definition of function tail, which returns the result of removing the first member of linked list L.
```
  Cell* tail(Cell* L)
  {
    Cell* p = L;
    Cell* answer = p->next;
    delete p;
    return answer;
  }
```
Answer
Explain why the following is not a correct definition of function addToFront, from a previous exercise.
```
  Cell* addToFront(int x, Cell* L)
  {
    Cell c;
    c.item = x;
    c.next = L;
    return &c;
  }
```
Answer

CSCI 3300 Spring 2009 Exercises for Quiz 6

CSCI 3300
Spring 2009
Exercises for Quiz 6