public ListNode DeleteDuplicates(ListNode head)
{
if (head == null || head.next == null)
return head;
ListNode newHead = new ListNode(-1);
newHead.next = head;
ListNode prev = newHead;
ListNode current = head;
while (current != null)
{
if (current.next != null && current.next.val == current.val)
{
while (current.next != null && current.next.val == current.val)
current = current.next;
prev.next = current.next;
current = current.next;
}
else
{
prev = prev.next;
current = current.next;
}
}
return newHead.next;
}
public ListNode Partition(ListNode head, int x)
{
if (head == null)
return null;
ListNode sm = new ListNode(0);
ListNode sm_tail = sm;
ListNode gt = new ListNode(0);
ListNode gt_tail = gt;
ListNode curr = head;
while (curr != null)
{
if (curr.val < x)
{
sm_tail.next = curr;
curr = curr.next;
sm_tail = sm_tail.next;
sm_tail.next = null;
}
else
{
gt_tail.next = curr;
curr = curr.next;
gt_tail = gt_tail.next;
gt_tail.next = null;
}
}
sm_tail.next = gt.next;
return sm.next;
}
public void OJ019_RemoveNthNodeFromEndOfListTest3()
{
ListNode l1 = new ListNode(1);
l1.next = new ListNode(2);
ListNode result = new OJ019_RemoveNthNodeFromEndOfList().RemoveNthFromEnd(l1, 2);
Assert.AreEqual(2, result.val);
}
public ListNode RotateRight(ListNode head, int k)
{
if (head == null || k == 0)
return head;
ListNode current = head;
int count = 0;
while (current != null)
{
count++;
current = current.next;
}
k = k % count;
if (k == 0)
return head;
ListNode first = head;
while (k-- > 0)
first = first.next;
ListNode second = head;
while (first.next != null)
{
first = first.next;
second = second.next;
}
ListNode result = second.next;
first.next = head;
second.next = null;
return result;
}
public ListNode ReverseBetween(ListNode head, int m, int n)
{
if (head == null)
return null;
ListNode prev = null;
ListNode current = head;
ListNode next = null;
int i = 0;
for (; i < m - 1; i++)
{
prev = current;
current = current.next;
}
ListNode h = prev;
ListNode hn = current;
for (; i < n && current != null; i++)
{
next = current.next;
current.next = prev;
prev = current;
current = next;
}
if (h != null)
h.next = prev;
else
head = prev;
hn.next = current;
return head;
}
public ListNode AddTwoNumbers(ListNode l1, ListNode l2)
{
ListNode result = new ListNode(0);
ListNode current = result;
while (true)
{
int sum = current.val;
if (l1 != null)
{
sum += l1.val;
l1 = l1.next;
}
if (l2 != null)
{
sum += l2.val;
l2 = l2.next;
}
current.val = sum % 10;
sum = sum / 10;
if (l1 != null || l2 != null || sum != 0)
{
current.next = new ListNode(sum);
current = current.next;
}
else
break;
}
return result;
}
public ListNode SwapPairs(ListNode head)
{
if (head == null || head.next == null)
return head;
ListNode first = head;
ListNode second = head.next;
head = second;
ListNode prev = null;
while (first != null && second != null)
{
first.next = second.next;
second.next = first;
if (prev != null)
{
prev.next = second;
}
prev = first;
first = first.next;
if (first != null)
second = first.next;
}
return head;
}
public void OJ083_RemoveDuplicatesFromSortedListTest3()
{
ListNode ln = new ListNode(1);
ln.Next(1).Next(1);
ListNode result = new OJ083_RemoveDuplicatesFromSortedList().DeleteDuplicates(ln);
Assert.AreEqual(1, ln.val);
Assert.AreEqual(null, ln.next);
}
public void OJ024_SwapNodesInPairsTest2()
{
ListNode l1 = new ListNode(1);
l1.next = new ListNode(2);
ListNode result = new OJ024_SwapNodesInPairs().SwapPairs(l1);
Assert.AreEqual(2, result.val);
Assert.AreEqual(1, result.next.val);
}
public void OJ082_RemoveDuplicatesFromSortedListIITest2()
{
ListNode ln = new ListNode(1);
ln.Next(1).Next(1).Next(2).Next(3);
ListNode result = new OJ082_RemoveDuplicatesFromSortedListII().DeleteDuplicates(ln);
Assert.AreEqual(2, result.val);
Assert.AreEqual(3, result.next.val);
Assert.AreEqual(null, result.next.next);
}
public void OJ109_ConvertSortedListToBinarySearchTreeTest1()
{
ListNode n = new ListNode(1);
n.Next(2).Next(3).Next(4).Next(5).Next(6);
TreeNode result = new OJ109_ConvertSortedListToBinarySearchTree().SortedListToBST(n);
Assert.AreEqual(3, result.val);
Assert.AreEqual(1, result.left.val);
Assert.AreEqual(2, result.left.right.val);
Assert.AreEqual(5, result.right.val);
Assert.AreEqual(4, result.right.left.val);
Assert.AreEqual(6, result.right.right.val);
}
public void OJ086_PartitionListTest1()
{
ListNode ln = new ListNode(1);
ln.Next(4).Next(3).Next(2).Next(5).Next(2);
ListNode result = new OJ086_PartitionList().Partition(ln, 3);
Assert.AreEqual(1, result.val);
Assert.AreEqual(2, result.next.val);
Assert.AreEqual(2, result.next.next.val);
Assert.AreEqual(4, result.next.next.next.val);
Assert.AreEqual(3, result.next.next.next.next.val);
Assert.AreEqual(5, result.next.next.next.next.next.val);
Assert.AreEqual(null, result.next.next.next.next.next.next);
}
public ListNode ReverseList(ListNode head)
{
ListNode prev = null;
ListNode current = head;
ListNode next = null;
while (current != null)
{
next = current.next;
current.next = prev;
prev = current;
current = next;
}
return prev;
}
public void OJ025_ReverseNodesInKGroup2()
{
ListNode l1 = new ListNode(1);
l1.next = new ListNode(2);
l1.next.next = new ListNode(3);
l1.next.next.next = new ListNode(4);
l1.next.next.next.next = new ListNode(5);
ListNode result = new OJ025_ReverseNodesInKGroup().ReverseKGroup(l1, 3);
Assert.AreEqual(3, result.val);
Assert.AreEqual(2, result.next.val);
Assert.AreEqual(1, result.next.next.val);
Assert.AreEqual(4, result.next.next.next.val);
Assert.AreEqual(5, result.next.next.next.next.val);
Assert.AreEqual(null, result.next.next.next.next.next);
}
public void OJ206_ReverseLinkedListTest1()
{
ListNode l1 = new ListNode(1);
l1.next = new ListNode(2);
l1.next.next = new ListNode(3);
l1.next.next.next = new ListNode(4);
l1.next.next.next.next = new ListNode(5);
ListNode result = new OJ206_ReverseLinkedList().ReverseList(l1);
Assert.AreEqual(5, result.val);
Assert.AreEqual(4, result.next.val);
Assert.AreEqual(3, result.next.next.val);
Assert.AreEqual(2, result.next.next.next.val);
Assert.AreEqual(1, result.next.next.next.next.val);
Assert.AreEqual(null, result.next.next.next.next.next);
}
public void OJ024_SwapNodesInPairsTest1()
{
ListNode l1 = new ListNode(1);
l1.next = new ListNode(2);
l1.next.next = new ListNode(3);
l1.next.next.next = new ListNode(4);
l1.next.next.next.next = new ListNode(5);
ListNode result = new OJ024_SwapNodesInPairs().SwapPairs(l1);
Assert.AreEqual(2, result.val);
Assert.AreEqual(1, result.next.val);
Assert.AreEqual(4, result.next.next.val);
Assert.AreEqual(3, result.next.next.next.val);
Assert.AreEqual(5, result.next.next.next.next.val);
Assert.AreEqual(null, result.next.next.next.next.next);
}
public void OJ002_AddTwoNumbersTest2()
{
ListNode l1 = new ListNode(1);
ListNode l2 = new ListNode(9);
l2.next = new ListNode(9);
ListNode l3 = new ListNode(0);
l3.next = new ListNode(0);
l3.next.next = new ListNode(1);
ListNode result = new OJ002_AddTwoNumbers().AddTwoNumbers(l1, l2);
Assert.AreEqual(l3.val, result.val);
Assert.AreEqual(l3.next.val, result.next.val);
Assert.AreEqual(l3.next.next.val, result.next.next.val);
Assert.IsNull(result.next.next.next);
}
private TreeNode generateBST(ListNode begin, ListNode end)
{
if (begin == end)
return null;
ListNode currentNode = begin;
ListNode currentNodeHalf = begin;
int i = 0;
while (currentNode.next != end)
{
if (++i % 2 == 0)
currentNodeHalf = currentNodeHalf.next;
currentNode = currentNode.next;
}
TreeNode node = new TreeNode(currentNodeHalf.val);
node.left = generateBST(begin, currentNodeHalf);
node.right = generateBST(currentNodeHalf.next, end);
return node;
}
public void OJ002_AddTwoNumbersTest1()
{
ListNode l1 = new ListNode(2);
l1.next = new ListNode(4);
l1.next.next = new ListNode(3);
ListNode l2 = new ListNode(5);
l2.next = new ListNode(6);
l2.next.next = new ListNode(4);
ListNode l3 = new ListNode(7);
l3.next = new ListNode(0);
l3.next.next = new ListNode(8);
ListNode result = new OJ002_AddTwoNumbers().AddTwoNumbers(l1, l2);
Assert.AreEqual(l3.val, result.val);
Assert.AreEqual(l3.next.val, result.next.val);
Assert.AreEqual(l3.next.next.val, result.next.next.val);
Assert.IsNull(result.next.next.next);
}
public ListNode DeleteDuplicates(ListNode head)
{
if (head == null)
return null;
ListNode prev = head;
ListNode current = head.next;
while (current != null)
{
if (current.val == prev.val)
{
prev.next = current.next;
}
else
{
prev = current;
}
current = current.next;
}
return head;
}
public void OJ021_MergeTwoSortedLists1()
{
ListNode l1 = new ListNode(1);
l1.next = new ListNode(3);
l1.next.next = new ListNode(12);
l1.next.next.next = new ListNode(14);
l1.next.next.next.next = new ListNode(15);
ListNode l2 = new ListNode(2);
l2.next = new ListNode(8);
l2.next.next = new ListNode(12);
ListNode result = new OJ021_MergeTwoSortedLists().MergeTwoLists(l1, l2);
Assert.AreEqual(1, result.val);
Assert.AreEqual(2, result.next.val);
Assert.AreEqual(3, result.next.next.val);
Assert.AreEqual(8, result.next.next.next.val);
Assert.AreEqual(12, result.next.next.next.next.val);
Assert.AreEqual(12, result.next.next.next.next.next.val);
Assert.AreEqual(14, result.next.next.next.next.next.next.val);
Assert.AreEqual(15, result.next.next.next.next.next.next.next.val);
Assert.AreEqual(null, result.next.next.next.next.next.next.next.next);
}
public ListNode RemoveNthFromEnd(ListNode head, int n)
{
if (head == null)
return null;
ListNode p1 = head;
ListNode p2 = head;
int i = n;
while (i-- > 0)
p1 = p1.next;
if (p1 == null)
return p2.next;
while (p1.next != null)
{
p1 = p1.next;
p2 = p2.next;
}
p2.next = p2.next.next;
return head;
}
public ListNode MergeTwoLists(ListNode l1, ListNode l2)
{
if (l1 == null && l2 == null)
return null;
ListNode lResult = new ListNode(0);
ListNode l = lResult;
while (true)
{
if (l1 == null)
{
l.next = l2;
return lResult.next;
}
else if (l2 == null)
{
l.next = l1;
return lResult.next;
}
else
{
if (l1.val < l2.val)
{
l.next = l1;
l1 = l1.next;
}
else
{
l.next = l2;
l2 = l2.next;
}
l = l.next;
}
}
}
public TreeNode SortedListToBST(ListNode head)
{
if (head == null)
return null;
return this.generateBST(head, null);
}
public void OJ019_RemoveNthNodeFromEndOfListTest2()
{
ListNode l1 = new ListNode(1);
ListNode result = new OJ019_RemoveNthNodeFromEndOfList().RemoveNthFromEnd(l1, 1);
Assert.AreEqual(null, result);
}
public static ListNode Next(this ListNode prev, int x)
{
ListNode node = new ListNode(x);
prev.next = node;
return node;
}
