## CTCI - Linked Lists Question 3
## Delete middle element, given only access to that element
import sys
sys.path.append('./classes')
from myllist import LinkedList
def deleteMiddleElmt(mnode):
if mnode is None or mnode.next is None:
return
curr = mnode
nextElmt = mnode.next
while nextElmt.next:
tmp = curr.next
curr.val = nextElmt.val
curr = tmp
nextElmt = tmp.next
curr.val = nextElmt.val
curr.next = None
list1 = LinkedList()
for n in [1, 2, 3, 4, 5]:
list1.append(n)
middleNode = list1.getNode(3)
list1.printList()
deleteMiddleElmt(middleNode)
list1.printList()
def returnLoopNode(head):
if head is None:
return None
itemSet = Set()
runner = head
itemSet.add(head)
while runner.next:
if runner.next in itemSet:
return runner.next
itemSet.add(runner.next)
runner = runner.next
return None
list1 = LinkedList()
for n in [1, 2, 3, 4, 5, 6]:
list1.append(n)
endNode = list1.getNode(5)
loopNode = list1.getNode(2)
endNode.next = loopNode
headNode = list1.getHeadNode()
result = returnLoopNode(headNode)
if result:
print result.val
else:
print result