//Deletes middle node when given the Head as input
public static void S2_3_DeleteMiddleNode(LinkedNode2 node)
{
var length = 0;
LinkedNode2 runner = node;
while (runner != null)
{
length++;
runner = runner.Next;
}
if (length < 3)
{
return;
}
runner = node;
var middle = length / 2;
for (int i = 1; i < middle; i++)
{
runner = runner.Next;
}
runner.Next = runner.Next.Next;
}
public static LinkedNode2 S2_4_Partition(LinkedNode2 head, int part)
{
LinkedNode2 prev = null;
var curr = head;
//iterate through Node
while (curr != null)
{
//if node is >= to partition, move to next node
if (curr.Data >= part)
{
prev = curr;
curr = curr.Next;
} //Else move current noe the head
else
{
//temp save curr
var oldCurr = curr;
//remove curr from current postion
curr = curr.Next;
prev.Next = curr;
//Make curr the new head
//Have ex-curr.Next point to head
var oldHead = head;
oldCurr.Next = oldHead;
//Set ex-curr as the new head
head = oldCurr;
}
}
//return node
return(head);
}
public static LinkedNode2 S2_4_Partition3(LinkedNode2 node, int part)
{
LinkedNode2 head = node;
LinkedNode2 tail = node;
while (node != null)
{
var next = node.Next;
//Move to tail if less than partition
if (node.Data < part)
{
node.Next = head;
head = node;
}
else
{
tail.Next = node;
tail = node;
}
node = next;
}
//nt sure why this is needed:
tail.Next = null;
return(head);
}
public static void S2_6_IsPalindrome_Test()
{
var input = new int[] { 1, 2, 3, 4, 5, };
var node = LinkedNode2.CreateFromList(input);
node.PrintNodes();
var reversed = LinkedNode2.Reverse(node);
reversed.PrintNodes();
}
//Deletes middle node when given that middle Node only
public static void S2_3_DeleteNode(LinkedNode2 node)
{
if (node == null || node.Next != null)
{
return;
}
var next = node.Next;
node.Data = next.Data;
node.Next = next.Next;
}
public static LinkedNode2 CreateFromList(IList <int> vals)
{
var head = new LinkedNode2(vals[0]);
var curr = head;
for (int i = 1; i < vals.Count; i++)
{
curr.Next = new LinkedNode2(vals[i]);
curr = curr.Next;
}
return(head);
}
public static int PrintKtoLastElement(LinkedNode2 node, int k)
{
if (node == null)
{
return(0);
}
var currXtoLastIdx = PrintKtoLastElement(node.Next, k) + 1;
if (k == currXtoLastIdx)
{
//Print
Console.WriteLine(node.Data);
}
return(currXtoLastIdx);
}
public static bool S2_6_IsPalindrome(LinkedNode2 l)
{
var currR = LinkedNode2.Reverse(l);
LinkedNode2 currL = l;
while (currR != null && currL != null)
{
if (currR.Data != currL.Data)
{
return(false);
}
currR = currR.Next;
currL = currL.Next;
}
return(true);
}
public static LinkedNode2 Reverse(LinkedNode2 node)
{
var curr = node;
LinkedNode2 newHead = null, next = null;
while (curr.Next != null)
{
next = curr.Next;
curr.Next = newHead;
newHead = curr;
curr = next;
}
curr.Next = newHead;
return(curr);
}
public static void S2_1_RemoveDups(LinkedNode2 node)
{
var set = new HashSet <int>();
LinkedNode2 prev = null;
while (node != null)
{
if (set.Contains(node.Data))
{
prev.Next = node.Next;
}
else
{
set.Add(node.Data);
prev = node;
}
node = node.Next;
}
}
public static LinkedNode2 S2_4_Partition2(LinkedNode2 head, int partition)
{
LinkedNode2 prePart = null;
LinkedNode2 postPart = null;
var curr = head;
while (curr != null)
{
if (curr.Data < partition)
{
if (prePart == null)
{
prePart = curr;
}
else
{
prePart.Next = curr;
prePart = prePart.Next;
}
}
else
{
if (postPart == null)
{
postPart = curr;
}
else
{
postPart.Next = curr;
postPart = postPart.Next;
}
}
}
if (prePart != null)
{
prePart.Next = postPart;
}
return(prePart == null
? postPart
: prePart);
}
public static bool S2_6_IsPalindrome3(LinkedNode2 l)
{
LinkedNode2 slow = l, fast = l;
var stack = new Stack <int>();
//iterate through node w/slow & fast runner until fast reaches end
while (fast != null && fast.Next != null)
{
//add slow's data to Stack
stack.Push(slow.Data);
slow = slow.Next;
fast = fast.Next.Next;
//when fast reaches end, slow should be in middle
}
//Figure if we need to skip middle
if (fast != null)
{
slow = slow.Next;
}
//Continue iterating using slow runner
while (slow != null)
{
//compare slow node w/stack vals
if (slow.Data != stack.Pop())
{
return(false);
}
//if diff found, return false
slow = slow.Next;
}
return(true);
}
public static void S2_2_RemoveKtoLast(LinkedNode2 node, int k)
{
var length = 0;
var runner = node;
while (runner != null)
{
length++;
runner = runner.Next;
}
if (length < k)
{
return;
}
runner = node;
for (int i = 1; i < length - k; i++)
{
runner = runner.Next;
}
runner.Next = runner.Next.Next;
}
public static LinkedNode2 S2_5_SumList(LinkedNode2 n1, LinkedNode2 n2)
{
LinkedNode2 result = null;
LinkedNode2 resultHead = null;
var carryover = 0;
//iterate through lls
while (n1 != null || n2 != null)
{
//add vals & carryover
var sum = carryover + (n1 == null ? 0 : n1.Data) + (n2 == null ? 0 : n2.Data);
//if > 9, set carryover to 1
carryover = sum > 9 ? 1 : 0;
if (carryover == 1)
{
sum = sum % 10;
}
if (result == null)
{
result = new LinkedNode2(sum);
resultHead = result;
}
else
{
result.Next = new LinkedNode2(sum);
}
n1 = n1.Next == null ? null : n1.Next;
n2 = n2.Next == null ? null : n2.Next;
}
//continue until all items are added
//return new string
return(resultHead);
}
