def main():
# test
A = ListNode('A')
B = ListNode('B')
C = ListNode('C')
D = ListNode('D')
E = ListNode('E')
F = ListNode('F')
G = ListNode('G')
A.next, B.next, C.next, D.next, E.next, F.next = B, C, D, E, F, G
G.next = B
# print(A.traverse()) #this will enter a loop when linked list has a cycle
print(has_cycle(A))
print(has_cycle_inplace(A))
def reverseList(self, head: ListNode) -> ListNode:
tmpNode = head
newNode = None
while tmpNode != None:
newFlagListNode = ListNode(tmpNode.val)
newFlagListNode.next = newNode
newNode = newFlagListNode
tmpNode = tmpNode.next
return newNode
def num2linked(num: int) -> ListNode:
if not num:
return ListNode(0)
curr = None
while num:
node = ListNode(num % 10)
if curr is not None:
node.next = curr
curr = node
num //= 10
return curr
def addTwoNumbers(self, l1: ListNode, l2: ListNode) -> ListNode:
# Baseline t o(n), s o(n)
summation = ListNode(0)
head = summation
carry = 0
while (l1 is not None or l2 is not None):
n1 = 0
if (l1 is not None):
n1 = l1.value()
l1 = l1.next()
n2 = 0
if (l2 is not None):
n2 = l2.value()
l2 = l2.next()
summation.next = ListNode((n1 + n2 + carry) % 10)
carry = (n1 + n2) // 10
summation = summation.next
if (carry > 0):
summation.next = ListNode(carry)
return (head.next)
def removeNthFromEnd2(head: ListNode, n: int) -> ListNode:
dummy = ListNode(-1)
dummy.next = head
node, i, dictionary = dummy, 0, {}
while node is not None:
dictionary[i] = node
i = i + 1
node = node.next
# print(i)
prev = dictionary[i - 1 - n]
prev.next = prev.next.next
return dummy.next # cannot return head as it can be removed
def removeNthFromEnd(head: ListNode, n: int) -> ListNode:
dummy = ListNode(-1)
dummy.next = head
node, i = dummy, 0
while node is not None:
i = i + 1
node = node.next
n = i - n - 1 # convert to nth from head
node = dummy
for i in range(n):
node = node.next
node.next = node.next.next
return dummy.next # cannot return head as it can be removed
def main():
# test
A = ListNode('A')
B = ListNode('B')
C = ListNode('C')
D = ListNode('D')
E = ListNode('E')
F = ListNode('F')
G = ListNode('G')
H = ListNode('H')
I = ListNode('I')
A.next, B.next, C.next, D.next = B, C, D, E
# E.next, F.next = F, D
print(A.traverse())
print(E.traverse())
def reverseBetween(head, m, n):
if not head:
return head
dummy = ListNode(-1)
dummy.next = head
m_prev = dummy
for i in range(m - 1):
m_prev = m_prev.next
m_cur = m_prev.next
rev_head = m_cur
for i in range(n - m):
next_ele = m_cur.next
next_link = next_ele.next
next_ele.next = rev_head
rev_head = next_ele
m_cur.next = next_link
m_prev.next = rev_head
return dummy.next
from listNode import ListNode
class Solution(object):
def removeNthFromEnd(self, head, n):
"""
:type head: ListNode
:type n: int
:rtype: ListNode
"""
if not head.next:
return
slow = fast = head
for i in range(n):
fast = fast.next
if not fast:
head = head.next
return head
while fast.next:
fast = fast.next
slow = slow.next
slow.next = slow.next.next
return head
node = ListNode(1)
node.next = ListNode(2)
result = Solution().removeNthFromEnd(node, 2)
print(result.val)
class Solution:
def reverseList(self, head: ListNode) -> ListNode:
tmpNode = head
newNode = None
while tmpNode != None:
newFlagListNode = ListNode(tmpNode.val)
newFlagListNode.next = newNode
newNode = newFlagListNode
tmpNode = tmpNode.next
return newNode
s = Solution()
head1 = ListNode(1)
head2 = ListNode(2)
head3 = ListNode(3)
head4 = ListNode(4)
head46 = ListNode(6)
head5 = ListNode(5)
head6 = ListNode(6)
head1.next = head2
head2.next = head3
head3.next = head4
head4.next = head46
head46.next = head5
head5.next = head6
print(head1)
newListNode = s.reverseList(head1)
print(newListNode)
def addTwoNumbers2(self,l1,l2):
carry = 0
root = n = ListNode(0)
while l1 or l2 or carry:
v1 = v2 = 0
if l1:
v1 = l1.val
l1 = l1.next
if l2:
v2 = l2.val
l2 = l2.next
carry, val = divmod(v1 + v2 + carry, 10)
n.next = ListNode(val)
n = n.next
return root.next
def printList(self,l1):
node = l1
while node:
print(node.val,end=',')
node=node.next
l1 = ListNode(2)
l1.next = ListNode(4)
l1.next.next = ListNode(3)
l2= ListNode(5)
l2.next = ListNode(6)
l2.next.next = ListNode(4)
lyst = Solution().addTwoNumbers(l1,l2)
Solution().printList(lyst)
def deleteNode(node: ListNode): # the node cannot be last one, so we can
node.val = node.next.val # set next node value to this one
node.next = node.next.next # then remove next node, this is tricky