public ListNode DeleteDuplicates(ListNode head)
{
if (head == null || head.next == null) return head;
ListNode dummy = head;
while (dummy.next != null)
{
if (dummy.next.val == dummy.val)
{
dummy.next = dummy.next.next;
}
else dummy = dummy.next;
}
return head;
}
public ListNode DeleteDuplicates(ListNode head)
{
if (head == null || head.next == null) return head;
ListNode fakedHead = new ListNode(-1);
fakedHead.next = head;
ListNode prevHead = fakedHead;
ListNode prevDiff = fakedHead.next;
while (prevDiff != null)
{
if (prevDiff.next != null && prevDiff.val == prevDiff.next.val)
{
int currV = prevDiff.val;
while (prevDiff.next != null)
{
prevDiff = prevDiff.next;
if (prevDiff.next == null || prevDiff.next.val != currV)
{
break;
}
}
}
if (prevHead.next == prevDiff)
{
prevHead = prevHead.next;
}
else
{
prevHead.next = prevDiff.next;
}
prevDiff = prevDiff.next;
// else
// {
// prevHead.next = prevDiff;
// prevHead = prevHead.next;
//
// prevDiff = prevDiff.next;
// }
}
return fakedHead.next;
}
//相同的即是交点
public ListNode GetIntersectionNode(ListNode headA, ListNode headB)
{
ListNode p1 = headA;
ListNode p2 = headB;
if (p1 == null || p2 == null) return null;
while (p1 != null && p2 != null && p1 != p2)
{
p1 = p1.next;
p2 = p2.next;
if (p1 == p2) return p1;
if (p1 == null) p1 = headB;
if (p2 == null) p2 = headA;
}
return p1;
}
public ListNode RemoveNthFromEnd(ListNode head, int n)
{
ListNode head1 = head;
ListNode head2 = head;
while (n-- > 0)
{
head2 = head2.next;
}
if (head2 == null)
{
return head.next;
}
while (head2.next != null)
{
head1 = head1.next;
head2 = head2.next;
}
head1.next = head1.next.next;
return head;
// ListNode start = new ListNode(0);
// ListNode slow = start, fast = start;
// slow.next = head;
//
// //Move fast in front so that the gap between slow and fast becomes n
// for (int i = 1; i <= n + 1; i++)
// {
// fast = fast.next;
// }
// //Move fast to the end, maintaining the gap
// while (fast != null)
// {
// slow = slow.next;
// fast = fast.next;
// }
// //Skip the desired node
// slow.next = slow.next.next;
// return start.next;
}
public void Execute()
{
ListNode node1 = new ListNode(1);
ListNode node2 = new ListNode(1);
ListNode node3 = new ListNode(1);
// ListNode node4 = new ListNode(2);
// ListNode node5 = new ListNode(3);
// ListNode node6 = new ListNode(4);
// ListNode node7 = new ListNode(4);
node1.next = node2;
node2.next = node3;
node3.next = null;
// node2.next = node3;
// node3.next = node4;
// node4.next = node5;
// node5.next = node6;
// node6.next = node7;
// node7.next = null;
DeleteDuplicates(node1);
}
public ListNode MergeTwoLists(ListNode l1, ListNode l2)
{
if (l1 == null)
{
return(l2);
}
if (l2 == null)
{
return(l1);
}
if (l1.val < l2.val)
{
l1.next = MergeTwoLists(l1.next, l2);
return(l1);
}
else
{
l2.next = MergeTwoLists(l1, l2.next);
return(l2);
}
}
public void Execute()
{
ListNode node1 = new ListNode(1);
ListNode node2 = new ListNode(1);
ListNode node3 = new ListNode(1);
// ListNode node4 = new ListNode(2);
// ListNode node5 = new ListNode(3);
// ListNode node6 = new ListNode(4);
// ListNode node7 = new ListNode(4);
node1.next = node2;
node2.next = node3;
node3.next = null;
// node2.next = node3;
// node3.next = node4;
// node4.next = node5;
// node5.next = node6;
// node6.next = node7;
// node7.next = null;
DeleteDuplicates(node1);
}
public ListNode DeleteDuplicates(ListNode head)
{
if (head == null || head.next == null) return head;
ListNode fakedHead = new ListNode(-1);
fakedHead.next = head;
ListNode prevHead = fakedHead;
ListNode prevDiff = fakedHead.next;
while (prevDiff != null)
{
if (prevDiff.next != null && prevDiff.val == prevDiff.next.val)
{
int currV = prevDiff.val;
while (prevDiff.next != null)
{
prevDiff = prevDiff.next;
if (prevDiff.next == null || prevDiff.next.val != currV)
{
break;
}
}
}
if (prevHead.next == prevDiff)
{
prevHead = prevHead.next;
}
else
{
prevHead.next = prevDiff.next;
}
prevDiff = prevDiff.next;
}
return fakedHead.next;
}
public ListNode MergeTwoLists(ListNode l1, ListNode l2)
{
if (l1 == null)
{
return l2;
}
if (l2 == null)
{
return l1;
}
if (l1.val < l2.val)
{
l1.next = MergeTwoLists(l1.next, l2);
return l1;
}
else
{
l2.next = MergeTwoLists(l1, l2.next);
return l2;
}
}
public void DeleteNode(ListNode node)
{
ListNode next = node.next;
node.val = next.val;
node.next = next.next;
}