public void EmptyElementTest()
{
LinkedList emptyList = new LinkedList();
LinkedList actualRevertedList = Factory.GetLinkedListReverter().Reverse(emptyList);
Assert.AreSame(emptyList, actualRevertedList);
Assert.IsNull(actualRevertedList.Data);
Assert.IsNull(actualRevertedList.Next);
}
public void TwoElementTest()
{
LinkedList fistElement = new LinkedList();
fistElement.Data = 1;
LinkedList secondElement = new LinkedList() { Data = 2 };
fistElement.Next = secondElement; // { 1 } -> { 2 }
LinkedList actualRevertedList = Factory.GetLinkedListReverter().Reverse(fistElement);
Assert.IsNotNull(actualRevertedList);
Assert.AreEqual(2, actualRevertedList.Data); // { 2 // check } -> { 1 }
Assert.IsNotNull(actualRevertedList.Next); // { 2 } -> /*check*/ { 1 }
Assert.AreEqual(1, actualRevertedList.Next.Data); // { 2 } -> { 1 // check }
}
public void ThousandElenetsTest()
{
int elementsCount = 1000;
LinkedList root = new LinkedList();
LinkedList current = root;
for (int i = 0; i < elementsCount; i++)
{
current.Data = i;
current.Next = i == elementsCount - 1 ? null : new LinkedList();
current = current.Next;
}
LinkedList actualRevertedList = Factory.GetLinkedListReverter().Reverse(root);
for (int i = elementsCount - 1; i > 0; i--)
{
Assert.AreEqual( i, actualRevertedList.Data);
actualRevertedList = actualRevertedList.Next;
}
Assert.AreEqual(0, actualRevertedList.Data);
Assert.IsNull(actualRevertedList.Next);
}
/// <summary>
/// Invert the order of the elements in a<see cref="LinkedList"/>
/// </summary>
/// <param name="source">sequence of elements to revert</param>
/// <returns>a <see cref="LinkedList"/> with elements in reverse order.</returns>
/// <remarks> O(N): 4 * N assigments, N comparasions. </remarks>
public LinkedList Reverse(LinkedList source)
{
if (source == null)
{
throw new ArgumentNullException("source");
}
if (source.Next == null)
return source;
LinkedList current = source;
LinkedList previous = null;
do
{
LinkedList next = current.Next;
current.Next = previous;
previous = current;
current = next;
} while (current != null);
return previous;
}
public void OneElementTest()
{
LinkedList oneElementList = new LinkedList() { Data = 1 };
LinkedList actualRevertedList = Factory.GetLinkedListReverter().Reverse(oneElementList);
}