public ListNode Partition(ListNode head, int x)
{
ListNode bp = new ListNode(0);
ListNode bpp = bp;
ListNode sp = new ListNode(0);
ListNode spp = sp;
ListNode ptr = head;
while(ptr != null)
{
if (ptr.val < x)
{
bpp.next = ptr;
bpp = ptr;
}
else
{
spp.next = ptr;
spp = ptr;
}
ptr = ptr.next;
}
bpp.next = sp.next;
spp.next = null;
return bp.next;
}
public ListNode OddEvenList(ListNode head)
{
if (head == null || head.next == null)
return head;
ListNode odd = head;
ListNode even = head.next;
ListNode ptr = odd;
ListNode eptr = even;
while(ptr != null && eptr != null)
{
ptr.next = eptr.next;
if (ptr.next == null)
break;
ptr = ptr.next;
eptr.next = ptr.next;
eptr = eptr.next;
}
ptr.next = even;
return odd;
}
public ListNode RemoveNthFromEnd(ListNode head, int n)
{
ListNode ptr = head;
int count = 0;
if (head == null)
return null;
while (ptr != null)
{
ptr = ptr.next;
count++;
}
count -= n;
if (count == 0)
return head.next;
ptr = head;
while(count>1)
{
ptr = ptr.next;
count--;
}
ptr.next = ptr.next.next;
return head;
}
public ListNode ReverseList(ListNode head)
{
if (head == null || head.next == null)
return head;
var p = head;
var q = head.next;
head.next = null;
while (true)
{
if (q.next == null)
{
q.next = p;
break;
}
else
{
// p q->r
var r = q.next;
// p<-q r
q.next = p;
p = q;
q = r;
}
}
return q;
}
public ListNode GetIntersectionNode(ListNode headA, ListNode headB)
{
ListNode ptrA = headA;
ListNode ptrB = headB;
bool flagA = true;
bool flagB = true;
if (headA == null || headB == null)
return null;
while (ptrA != null && ptrB != null)
{
if (ptrA == ptrB)
return ptrA;
ptrA = ptrA.next;
ptrB = ptrB.next;
if (ptrA == null && flagA)
{
ptrA = headB;
flagA = false;
}
if (ptrB == null && flagB)
{
ptrB = headA;
flagB = false;
}
}
return null;
}
public ListNode RotateRight(ListNode head, int k)
{
ListNode tail = head;
int len = 1;
if (k == 0 || head == null)
return head;
while (tail.next != null)
{
len++;
tail = tail.next;
}
k = len - k % len;
if (k == len)
return head;
tail.next = head;
len = 1;
tail = head;
while(len < k)
{
tail = tail.next;
len++;
}
head = tail.next;
tail.next = null;
return head;
}
public void ReorderList(ListNode head)
{
if (head == null || head.next == null)
return;
ListNode p = head;
ListNode pre = p;
ListNode ptr = head;
while(ptr != null && ptr.next != null)
{
pre = p;
p = p.next;
ptr = ptr.next.next;
}
pre.next = null;
p = ReverseList(p);
ptr = p;
pre = head;
while (p != null && head != null)
{
ptr = p.next;
pre = head.next;
head.next = p;
if (pre != null)
p.next = pre;
p = ptr;
head = pre;
}
}
public ListNode SortList(ListNode head)
{
if (head == null || head.next == null)
return head;
bool flag = true;
ListNode lefthead = head;
ListNode righthead = head.next;
ListNode left = lefthead;
ListNode right = righthead;
head = head.next.next;
while(head != null)
{
if (flag)
{
left.next = head;
left = left.next;
}
else
{
right.next = head;
right = right.next;
}
head = head.next;
flag = !flag;
}
left.next = null;
right.next = null;
left = SortList(lefthead);
right = SortList(righthead);
return merge(left, right);
}
public ListNode MergeKLists(ListNode[] lists)
{
int len = lists.Length;
if (len == 0)
return null;
while(len > 1)
{
int j = 0;
int pos = 0;
while(j+1 < len)
{
lists[pos] = MergeTwoLists(lists[j], lists[j + 1]);
j += 2;
pos++;
}
if (j<len)
{
lists[pos] = lists[j];
pos++;
}
len = pos;
}
return lists[0];
}
public ListNode MergeTwoLists(ListNode l1, ListNode l2)
{
ListNode head = new ListNode(-1);
ListNode cur = head;
if (l1 == null)
return l2;
else if (l2 == null)
return l1;
while(l1 != null && l2 != null)
{
if (l1.val <= l2.val)
{
cur.next = l1;
cur = cur.next;
l1 = l1.next;
}
else
{
cur.next = l2;
cur = cur.next;
l2 = l2.next;
}
}
if (l1 == null && l2 != null)
cur.next = l2;
else if (l1 != null && l2 == null)
cur.next = l1;
return head.next;
}
public TreeNode SortedListToBST(ListNode head)
{
if (head == null)
return null;
if (head.next == null)
return new TreeNode(head.val);
ListNode p = head;
ListNode q = head;
ListNode pre = q;
while(p != null && p.next != null)
{
pre = q;
q = q.next;
p = p.next.next;
}
TreeNode tn = new TreeNode(q.val);
if (q == head)
{
tn.right = new TreeNode(q.next.val);
}
else
{
tn = new TreeNode(q.val);
pre.next = null;
tn.left = SortedListToBST(head);
tn.right = SortedListToBST(q.next);
}
return tn;
}
public ListNode DetectCycle(ListNode head)
{
if (head == null || head.next == null)
return null;
ListNode p = head;
ListNode p2 = head.next;
while (p != null && p2 != null && p != p2)
{
p = p.next;
if (p2.next == null)
return null;
p2 = p2.next.next;
}
if (p != p2)
return null;
p2 = head;
while(p2 != p)
{
p = p.next;
p2 = p2.next;
}
return p2;
}
public ListNode AddTwoNumbers(ListNode l1, ListNode l2)
{
int flag = 0;
ListNode head = new ListNode(0);
ListNode tmp = null;
var re = head;
while (l1 != null && l2 != null)
{
int val = l1.val + l2.val + flag;
if (val >= 10)
{
flag = 1;
val -= 10;
}
else
flag = 0;
re.next = new ListNode(val);
re = re.next;
l1 = l1.next;
l2 = l2.next;
}
if (l1 != null)
tmp = l1;
else if (l2 != null)
tmp = l2;
while (tmp != null)
{
var val = tmp.val + flag;
if (val >= 10)
{
flag = 1;
val -= 10;
}
else
flag = 0;
re.next = new ListNode(val);
re = re.next;
tmp = tmp.next;
}
if (flag == 1)
{
re.next = new ListNode(1);
re.next.next = null;
}
else
re.next = null;
return head.next;
}
public void DeleteNode(ListNode node)
{
if (node.next == null)
return;
ListNode pre = null;
while(node.next != null)
{
node.val = node.next.val;
pre = node;
node = node.next;
}
pre.next = null;
}
public static void Run()
{
var st = new Solution61();
Console.WriteLine("Start: {0}", DateTime.Now);
ListNode p = new ListNode(1);
p.next = new ListNode(2);
p.next.next = new ListNode(3);
p.next.next.next = new ListNode(4);
var re = st.RotateRight(p, 4);
Util.PrintListNode(re);
Console.WriteLine("End: {0}", DateTime.Now);
}
public ListNode SwapPairs(ListNode head)
{
ListNode re = head;
if (head == null || head.next == null)
return head;
re = head.next;
head.next = re.next;
re.next = head;
head.next = SwapPairs(head.next);
return re;
}
public static void Run()
{
var st = new Solution83();
Console.WriteLine("Start: {0}", DateTime.Now);
ListNode p = new ListNode(1);
p.next = new ListNode(1);
p.next.next = new ListNode(2);
p.next.next.next = new ListNode(4);
p.next.next.next.next = null;
Util.PrintListNode(st.DeleteDuplicates(p));
Console.WriteLine("End: {0}", DateTime.Now);
}
public static void Run()
{
var st = new Solution19();
Console.WriteLine("Start: {0}", DateTime.Now);
ListNode p = new ListNode(1);
p.next = new ListNode(2);
p.next.next = new ListNode(3);
p.next.next.next = new ListNode(4);
p.next.next.next.next = null;
Util.PrintListNode(st.RemoveNthFromEnd(p, 3));
Util.PrintListNode(st.RemoveNthFromEnd(p, 2));
Console.WriteLine("End: {0}", DateTime.Now);
}
public static void PrintListNode(ListNode p)
{
if (p == null)
Console.WriteLine("<null>");
else while (true)
{
Console.Write("{0} -> ", p.val);
if (p.next == null)
{
Console.WriteLine("<end>");
break;
}
else
p = p.next;
}
}
public static void Run()
{
var st = new Solution234();
ListNode lt = new ListNode(1);
lt.next = new ListNode(2);
lt.next.next = new ListNode(3);
lt.next.next.next = new ListNode(2);
lt.next.next.next.next = new ListNode(1);
lt.next.next.next.next.next = null;
Console.WriteLine("Start: {0}", DateTime.Now);
var re = st.IsPalindrome(lt);
Console.WriteLine("{0}", re);
Console.WriteLine("End: {0}", DateTime.Now);
}
public static void Run()
{
var st = new Solution143();
Console.WriteLine("Start: {0}", DateTime.Now);
ListNode p = new ListNode(1);
p.next = new ListNode(2);
p.next.next = new ListNode(3);
p.next.next.next = new ListNode(4);
p.next.next.next.next = new ListNode(5);
st.ReorderList(p);
Util.PrintListNode(p);
Console.WriteLine("End: {0}", DateTime.Now);
}
public static void Run()
{
var st = new Solution86();
Console.WriteLine("Start: {0}", DateTime.Now);
ListNode p = new ListNode(1);
p.next = new ListNode(4);
p.next.next = new ListNode(3);
p.next.next.next = new ListNode(2);
p.next.next.next.next = new ListNode(5);
p.next.next.next.next.next = new ListNode(2);
Util.PrintListNode(st.Partition(p, 3));
Console.WriteLine("End: {0}", DateTime.Now);
}
public static void Run()
{
var st = new Solution21();
Console.WriteLine("Start: {0}", DateTime.Now);
ListNode p = new ListNode(1);
p.next = new ListNode(3);
p.next.next = null;
ListNode q = new ListNode(2);
q.next = new ListNode(4);
q.next.next = null;
Util.PrintListNode(st.MergeTwoLists(p, q));
Console.WriteLine("End: {0}", DateTime.Now);
}
public static void Run()
{
var st = new Solution24();
ListNode p = new ListNode(1);
p.next = new ListNode(2);
p.next.next = new ListNode(3);
p.next.next.next = new ListNode(4);
p.next.next.next.next = null;
Console.WriteLine("Start: {0}", DateTime.Now);
var re = st.SwapPairs(p);
Util.PrintListNode(re);
Console.WriteLine("End: {0}", DateTime.Now);
}
public ListNode RemoveElements(ListNode head, int val)
{
if (head == null)
return head;
ListNode fhead = new ListNode(0);
fhead.next = head;
ListNode ptr = fhead;
while (ptr.next != null)
{
if (ptr.next.val == val)
ptr.next = ptr.next.next;
else
ptr = ptr.next;
}
return fhead.next;
}
public static void Run()
{
var st = new Solution328();
Console.WriteLine("Start: {0}", DateTime.Now);
ListNode p = new ListNode(1);
p.next = new ListNode(2);
p.next.next = new ListNode(3);
p.next.next.next = new ListNode(4);
p.next.next.next.next = new ListNode(5);
//p.next.next.next.next.next = new ListNode(6);
Util.PrintListNode(st.OddEvenList(p));
Console.WriteLine("End: {0}", DateTime.Now);
}
public static void Run()
{
var st = new Solution147();
Console.WriteLine("Start: {0}", DateTime.Now);
ListNode p = new ListNode(5);
p.next = new ListNode(4);
p.next.next = new ListNode(6);
p.next.next.next = new ListNode(7);
p.next.next.next.next = new ListNode(8);
p = st.InsertionSortList(p);
Util.PrintListNode(p);
Console.WriteLine("End: {0}", DateTime.Now);
}
public static void Run()
{
var st = new Solution25();
Console.WriteLine("Start: {0}", DateTime.Now);
ListNode p1 = new ListNode(1);
p1.next = new ListNode(2);
p1.next.next = new ListNode(3);
p1.next.next.next = new ListNode(4);
//p1.next.next.next.next = new ListNode(5);
var re = st.ReverseKGroup(p1, 2);
Util.PrintListNode(re);
Console.WriteLine("End: {0}", DateTime.Now);
}
public static void Run()
{
var st = new Solution206();
Console.WriteLine("Start: {0}", DateTime.Now);
ListNode p = new ListNode(3);
p.next = new ListNode(4);
p.next.next = new ListNode(5);
p.next.next.next = null;
Util.PrintListNode(st.ReverseList(p));
var q = new ListNode(0);
q.next = null;
Util.PrintListNode(st.ReverseList(q));
Console.WriteLine("End: {0}", DateTime.Now);
}
public static void Run()
{
var st = new Solution237();
Console.WriteLine("Start: {0}", DateTime.Now);
ListNode p = new ListNode(1);
p.next = new ListNode(2);
ListNode q = new ListNode(3);
q.next = new ListNode(4);
q.next.next = null;
p.next.next = q;
st.DeleteNode(q);
Util.PrintListNode(p);
Console.WriteLine("End: {0}", DateTime.Now);
}