//Sort a linked list
public static Node InsertionSort(ref Node head)
{
//Head is the list I want to sort.
//Sorted is the new list I will build with insertions.
Node sorted = null;
Node newhead = null;
Node insertpoint = null;
while (head != null)
{
//The node currently at head needs to be sorted in.
//Find the location in sorted where I want this
//Add to head of sorted?
if(sorted == null || sorted.Value > head.Value)
{
//add to head
newhead = head.Next;
head.Next = sorted; //Insert sorted list after head
//Clean up pointers
sorted = head;
head = newhead;
}
//Otherwise, find insertion point
else
{
insertpoint = sorted;
while (insertpoint.Next != null && insertpoint.Next.Value < head.Value)
insertpoint = insertpoint.Next;
//insertpoint now at node before where I want to sort
newhead = head.Next;
head.Next = insertpoint.Next;
insertpoint.Next = head;
//Clean up pointers
head = newhead;
}
}
//head is null right now.
head = sorted;
return sorted;
}
static void Main(string[] args)
{
Random r = new Random();
int collSize = 10;
//Create a random array
int[] values = new int[collSize];
for (int i = 0; i < collSize; ++i)
values[i] = r.Next(collSize);
//Print 'em
Console.WriteLine();
Console.WriteLine("Array\n====");
PrintArray(values);
SelectionSort(values);
PrintArray(values);
Console.WriteLine("Array is " + (isSorted(values) ? "sorted." : "not sorted."));
//create a random list
Node head = null;
for(int i = 0; i < collSize; ++i)
{
//just going to add to head
Node newHead = new Node();
newHead.Value = r.Next(collSize);
newHead.Next = head;
head = newHead;
}
//Print 'em
Console.WriteLine();
Console.WriteLine("List\n====");
PrintList(head);
InsertionSort(ref head);
PrintList(head);
Console.WriteLine("List is " + (isSorted(head) ? "sorted." : "not sorted."));
//Pause
Console.ReadKey();
}
public static bool isSorted(Node head)
{
if (head == null) return true;
if (head.Next == null) return true;
return ((head.Next.Value >= head.Value) && isSorted(head.Next));
}
public static void PrintList(Node head)
{
if (head != null)
{
Console.Write(head.Value + " ");
PrintList(head.Next);
}
else Console.WriteLine();
}