public ListNode GetIntersectionNode(ListNode headA, ListNode headB)
{
if (headA == null || headB == null)
return null;
var countA = Count(headA);
var countB = Count(headB);
if (countA > countB)
for (int i = 0; i < countA - countB; i++)
headA = headA.next;
else if (countA < countB)
for (int i = 0; i < countB - countA; i++)
headB = headB.next;
ListNode result = null;
while (headA != null)
{
if (headA.val == headB.val)
{
if (result == null)
result = headA;
}
else
result = null;
headA = headA.next;
headB = headB.next;
}
return result;
}
public ListNode RemoveNthFromEnd(ListNode head, int n)
{
ListNode t = head;
ListNode p = head;
if (head == null)
return null;
else if (head.next == null && n > 0)
return null;
for (int i = 0; i < n - 1; i++)
t = t.next;
if (t.next == null)
return head.next;
else
t = t.next;
while (true)
{
if (t.next == null)
{
if (p.next == head)
return head.next;
else
p.next = p.next.next;
break;
}
else
{
p = p.next;
t = t.next;
}
}
return head;
}
private int Count(ListNode head)
{
if (head == null)
return 0;
int count = 0;
while (head != null)
{
count++;
head = head.next;
}
return count;
}
public ListNode DeleteDuplicates(ListNode head)
{
if (head == null)
return null;
var node = head;
while (node.next != null)
{
if (node.val == node.next.val)
node.next = node.next.next;
else
node = node.next;
}
return head;
}
public bool HasCycle(ListNode head)
{
if (head == null || head.next == null)
return false;
var slowpoint = head;
var fastpoint = head;
while (true)
{
if (fastpoint.next != null && fastpoint.next.next != null)
{
fastpoint = fastpoint.next.next;
slowpoint = slowpoint.next;
if (fastpoint == slowpoint)
return true;
}
else
return false;
}
}
private bool Check(ListNode current, ref ListNode head, ref bool isover)
{
//start to compare, it's the end of the linkedlist
if (current == null)
return true;
var result = Check(current.next, ref head, ref isover);
if (result == false)
return false;
else if (isover)
return true;
else if (current.val != head.val)
return false;
else
{
if (head == current || head.next == current)
isover = true;
else
head = head.next;
return true;
}
}
public ListNode ReverseList(ListNode head)
{
if (head == null || head.next == null)
return head;
else
{
var p1 = head;
var p2 = head.next;
var p3 = head.next.next;
p1.next = null;
while (p2 != null)
{
p2.next = p1;
if (p3 == null)
break;
p1 = p2;
p2 = p3;
p3 = p2.next;
}
return p2;
}
}
public ListNode RemoveElements(ListNode head, int val)
{
while (head != null && head.val == val)
head = head.next;
if (head == null)
return null;
else if (head.next == null)
return head;
else
{
var p = head;
while (p.next.next != null)
{
if (p.next.val == val)
p.next = p.next.next;
else
p = p.next;
}
if (p.next.val == val)
p.next = null;
return head;
}
}
public bool IsPalindrome(ListNode head)
{
bool isover = false;
return Check(head, ref head, ref isover);
}
public ListNode(int x)
{
val = x;
next = null;
}
public void DeleteNode(ListNode node)
{
node.val = node.next.val;
node.next = node.next.next;
}