public ListNode DeleteDuplicates(ListNode head)
{
ListNode dumHead = new ListNode(0), slow, fast;
dumHead.next = head;
slow = dumHead;
fast = head;
int fastStep = 0;
while (fast != null && fast.next != null)
{
if (fast.next.val != fast.val)
{
if (fastStep > 0)
{
slow.next = fast.next;
fast = fast.next;
fastStep = 0;
}
else
{
fast = fast.next;
slow = slow.next;
}
}
else
{
fast = fast.next;
fastStep++;
}
}
if (slow.next != fast)
{
slow.next = null;
}
return(dumHead.next);
}
public ListNode ReverseBetween(ListNode head, int m, int n)
{
if (head == null)
{
return(null);
}
ListNode pre = null, cur = head, dumHead = new ListNode(0), newHead = dumHead, newTail = null;
dumHead.next = head;
int counter = 1;
while (cur != null && counter <= n)
{
if (counter >= m)
{
newTail = counter == m ? cur : newTail;
ListNode tmp = cur.next;
cur.next = pre;
pre = cur;
cur = tmp;
}
else
{
cur = cur.next;
newHead = newHead.next;
}
counter++;
}
newHead.next = pre;
newTail.next = cur;
return(dumHead.next);
}
public ListNode Partition(ListNode head, int x)
{
if (head == null)
{
return(null);
}
ListNode current = head, leftHead = null, leftTail = null, rightHead = null, rightTail = null;
while (current != null)
{
ListNode tmp = new ListNode(current.val);
if (current.val < x)
{
if (leftHead == null)
{
leftHead = tmp;
leftTail = tmp;
}
else
{
leftTail.next = tmp;
leftTail = leftTail.next;
}
}
else
{
if (rightHead == null)
{
rightHead = tmp;
rightTail = tmp;
}
else
{
rightTail.next = tmp;
rightTail = rightTail.next;
}
}
current = current.next;
}
if (leftTail != null)
{
leftTail.next = rightHead;
return(leftHead);
}
return(rightHead);
}
