public DoubleNode <int> LinkedListForPartitionTests()
{
var a = new DoubleNode <int>(1);
var b = new DoubleNode <int>(2);
var c = new DoubleNode <int>(3);
var d = new DoubleNode <int>(6);
var e = new DoubleNode <int>(9);
var f = new DoubleNode <int>(22);
var g = new DoubleNode <int>(12);
var h = new DoubleNode <int>(10);
a.previous = null;
a.next = b;
b.previous = a;
b.next = c;
c.previous = b;
c.next = d;
d.previous = c;
d.next = e;
e.previous = d;
e.next = f;
f.previous = e;
f.next = g;
g.previous = f;
g.next = h;
h.previous = g;
h.next = null;
return(a);
}
public void PartitionTest1()
{
var part = new Partition();
var a = new DoubleNode <int>(1);
var b = new DoubleNode <int>(2);
var c = new DoubleNode <int>(3);
var d = new DoubleNode <int>(6);
var e = new DoubleNode <int>(22);
var f = new DoubleNode <int>(12);
var g = new DoubleNode <int>(10);
var h = new DoubleNode <int>(9);
a.previous = null;
a.next = b;
b.previous = a;
b.next = c;
c.previous = b;
c.next = d;
d.previous = c;
d.next = e;
e.previous = d;
e.next = f;
f.previous = e;
f.next = g;
g.previous = f;
g.next = h;
h.previous = g;
h.next = null;
var expected = a;
var actual = part.PartitionDoublyLL(LinkedListForPartitionTests(), 9);
Assert.AreEqual(expected, actual);
}
public override bool Equals(Object obj)
{
if (obj == null || GetType() != obj.GetType())
{
return(false);
}
DoubleNode <T> p = (DoubleNode <T>)obj;
return(p.ToString() == this.ToString());
}
public void ReverseList()
{
var reverse = new DoubleNode <char>();
var expected = new List <char>()
{
'd', 'c', 'b', 'a'
};
var actual = reverse.ReverseList(SampleList());
Assert.AreEqual(expected, actual);
}
/*
* Implement an algorithm to delete a node in the middle (i.e any node but the first and the and lsat node, not necessarily exact middle)
* of a singly linked list, given only access to that node.
*/
public DoubleNode <char> DeleteMidNode(DoubleNode <char> n, char k)
{
var current = n;
while (current != null)
{
if (current.value == k)
{
current.previous.next = current.next;
current.next.previous = current.previous;
}
current = current.next;
}
return(n);
}
public DoubleNode <char> ReturnNodes(DoubleNode <char> n, char k)
{
DoubleNode <char> alternateNode = null;
DoubleNode <char> currentNode = n;
while (currentNode != null)
{
if (currentNode.value == k)
{
alternateNode = currentNode;
return(alternateNode);
}
currentNode = currentNode.next;
}
return(alternateNode);
}
public DoubleNode <char> sampleDoubleLinkedNode()
{
var a = new DoubleNode <char>('a');
var b = new DoubleNode <char>('b');
var c = new DoubleNode <char>('c');
var d = new DoubleNode <char>('d');
a.previous = null;
a.next = b;
b.previous = a;
b.next = c;
c.previous = b;
c.next = d;
d.previous = c;
d.next = null;
return(a);
}
public DoubleNode <char> ReversedDoubleLinkedList()
{
var d = new DoubleNode <char>('d');
var c = new DoubleNode <char>('c');
var b = new DoubleNode <char>('b');
var a = new DoubleNode <char>('a');
d.previous = null;
d.next = c;
c.previous = d;
c.next = b;
b.previous = c;
b.next = a;
a.previous = b;
a.next = null;
return(d);
}
public void ReturnPartOfALinkedListTest()
{
var remove = new ReturnKthToLast();
var c = new DoubleNode <char>('c');
var d = new DoubleNode <char>('d');
var e = new DoubleNode <char>('e');
c.previous = null;
c.next = d;
d.previous = c;
d.next = e;
e.previous = d;
e.next = null;
var expected = c;
var actual = remove.ReturnNodes(MyLinkedList(), 'c');
Assert.AreEqual(expected, actual);
}
public DoubleNode <char> MyLinkedList()
{
var a = new DoubleNode <char>('a');
var b = new DoubleNode <char>('b');
var c = new DoubleNode <char>('c');
var d = new DoubleNode <char>('d');
var e = new DoubleNode <char>('e');
a.previous = null;
a.next = b;
b.previous = a;
b.next = c;
c.previous = b;
c.next = d;
d.previous = c;
d.next = e;
e.previous = d;
e.next = null;
return(a);
}
public void ToStringForDoublyLinkedNodes()
{
var a = new DoubleNode <char>('a');
var b = new DoubleNode <char>('b');
var c = new DoubleNode <char>('c');
var d = new DoubleNode <char>('d');
a.previous = null;
a.next = b;
b.previous = a;
b.next = c;
c.previous = b;
c.next = d;
d.previous = c;
d.next = null;
var expected = "a <-> b <-> c <-> d";
var actual = a.ToString();
Assert.AreEqual(expected, actual);
}
public void CountMethodForDoublyLinkedNodes()
{
var a = new DoubleNode <char>('a');
var b = new DoubleNode <char>('b');
var c = new DoubleNode <char>('c');
var d = new DoubleNode <char>('d');
a.previous = null;
a.next = b;
b.previous = a;
b.next = c;
c.previous = b;
c.next = d;
d.previous = c;
d.next = null;
var expected = 4;
var actual = a.Count();
Assert.AreEqual(expected, actual);
}
public DoubleNode <char> MyLinkedList() //this is a hard coded linked list... i was trying to figure out how to delcare and set the original linked list
//and manipulate it in the same method...
{
var a = new DoubleNode <char>('a');
var b = new DoubleNode <char>('b');
var c = new DoubleNode <char>('c');
var d = new DoubleNode <char>('d');
var e = new DoubleNode <char>('e');
a.previous = null;
a.next = b;
b.previous = a;
b.next = c;
c.previous = b;
c.next = d;
d.previous = c;
d.next = e;
e.previous = d;
e.next = null;
return(a);
}
public void DeleteMiddleNodeFromLinkedList()
{
var delete = new DeleteMiddleNode();
var a = new DoubleNode <char>('a');
var b = new DoubleNode <char>('b');
var c = new DoubleNode <char>('c');
var d = new DoubleNode <char>('d');
var e = new DoubleNode <char>('e');
a.previous = null;
a.next = b;
b.previous = a;
b.next = d;
d.previous = b;
d.next = e;
e.previous = d;
e.next = null;
var expected = a;
var actual = delete.DeleteMidNode(MyLinkedList(), 'c');
Assert.AreEqual(expected, actual);
}
/*
* "Write code to partition a linked list around a value x, such that all nodes less than x come before all nodes greater than or equal to x.
* If x is contained within the list, the values of x only need to be after the elements less than x (see below). The partition element x can appear anywhere in the
* "right partition"; it does not need to appear between the left and right partitions."
* Example: Input: 3 -> 5 -> 8 -> 5 -> 10 -> 2 -> 1 [partition 5]
* Output: 3 -> 1 -> 2 -> 10 -> 5 -> 5 -> 8
*
* it seems that there are a few ways to do this:
* sort the entire list and put the list in numerical order
* put the partition value(s) (in case there's more than one instnace of the partition, like above) at the end of the list
*
* the easiest thing to do that I can see if to remove the partition nodes, make a note of how many partitions there are (for example, what if there are
* 2 or 3 partitions, you still need all nodes accounted for (I'm thinking either a list and foreach through each element in the list, or have a count, and
* count-- and when the count is 1 or 0 and all the partition nodes have been accounted for and the appropriate nodes have been attached, return the linked list).
*
* I'm guessing that in order to add the partition nodes at the end of the linked list, I need to link them the previous nodes, and thus needing a DoubleNode?
* try a singly linked list first
*
*
* I realized that this algorithm only accounts for one instance of the partition value in a linked list... that is something I have to account for when redoing this one
*/
public DoubleNode <int> PartitionDoublyLL(DoubleNode <int> n, int partition)
{
var count = 0;
var partitionTail = new DoubleNode <int>();
while (n.next != null)
{
if (n.value == partition)
{
count++;
n.next.previous = n.previous;
n.previous.next = n.next;
n = n.next;
}
if (n.next != null)
{
n = n.next;
}
if (n.next == null)
{
//this is where I still have to mend some of my work, this only accounts for one of the nodes contianing the partition value, where there could be many
if (count == 1)
{
count--;
partitionTail.value = partition;
n.next = partitionTail;
partitionTail.next = null;
while (n.previous != null)
{
partitionTail.previous = n;
n = n.previous;
}
return(n);
}
}
}
return(n);
}
