from GeeksForGeeks.LinkedList.SinglyLinkedList import LinkedList
"""
function a revervse a linkedlist
"""
def reverse_ll(head):
"""
reversing the pointers for every node - Single traveral - O(n) time.
:param head
:return:
"""
prev = None
current = head
while current:
temp = current.next
current.next = prev
prev = current
current = temp
return prev
if __name__ == '__main__':
ll = LinkedList()
for i in range(5, 9):
ll.insert_at_ending(i)
ll.print_list()
ll.head = reverse_ll(ll.head)
ll.print_list()
current = head
next = None
prev = None
count = 0
while current and count < k:
next = current.next
current.next = prev
prev = current
current = next
count += 1
if next:
head.next = current
count = 0
while current and count < k - 1:
current = current.next
count += 1
if current:
current.next = reverse_alt_knodes(current.next, k)
return prev
if __name__ == '__main__':
ll = LinkedList()
for i in range(1, 10):
ll.insert_at_ending(i)
ll.head = reverse_alt_knodes(ll.head, 3)
ll.print_list()
from GeeksForGeeks.LinkedList.SinglyLinkedList import LinkedList
"""
Move last element to front of a given Linked List
Write a C function that moves last element to front in a given Singly Linked List. For example, if the given Linked
List is 1->2->3->4->5, then the function should change the list to 5->1->2->3->4.
"""
def move_nth(head):
if not head:
return
else:
current = head
prev = head
while current.next is not None:
prev = current
current = current.next
prev.next = None
current.next = head
head = current
return head
if __name__ == '__main__':
ll = LinkedList()
for i in range(1, 10):
ll.insert_at_ending(i)
ll.head = move_nth(ll.head)
ll.print_list()
def delete_nodes(head):
if not head:
return
else:
new_head = reverse(head)
current = new_head
_max = current.data
while current and current.next:
if current.next.data < _max and current.next:
current.next = current.next.next
else:
_max = current.data
current = current.next
head1 = reverse(new_head)
return head1
if __name__ == '__main__':
ll = LinkedList()
ll.insert_at_ending(12)
ll.insert_at_ending(15)
ll.insert_at_ending(10)
ll.insert_at_ending(11)
ll.insert_at_ending(5)
ll.insert_at_ending(6)
ll.insert_at_ending(2)
ll.insert_at_ending(3)
ll.head = delete_nodes(ll.head)
ll.print_list()
while current and count < k :
next = current.next
current.next = prev
prev = current
current = next
count += 1
if next :
head.next = reverse_in_groups(next,k)
return prev
if __name__=='__main__':
ll = LinkedList()
for i in range(1,3):
ll.insert_at_ending(i)
ll.head = reverse(ll.head)
#ll.print_list()
ll.head = reverse(ll.head)
ll.head = reverse_in_groups(ll.head,1)
ll.print_list()
return node
current = node.next
prev = node
node = current
while prev and current :
next = current.next
current.next = prev
if not next or not next.next :
prev.next = next
break
prev.next = next.next
prev = next
current = prev.next
return node
if __name__=='__main__':
ll = LinkedList()
for i in range(1,10):
ll.insert_at_ending(i)
#ll.print_list()
#pairwise_swap(ll.head)
#ll.print_list()
ll.head = _pairwise_swap(ll.head)
ll.print_list()
current = current.next
while cur2:
_sum = cur2.data + carry
carry = _sum // 10
_sum = _sum % 10
current.next = Node(_sum)
cur2 = cur2.next
current = current.next
if carry == 1:
current.next = Node(carry)
return new_head
if __name__ == '__main__':
ll1 = LinkedList()
ll1.insert_at_ending(3)
ll1.insert_at_ending(6)
ll1.insert_at_ending(5)
ll2 = LinkedList()
ll2.insert_at_ending(2)
ll2.insert_at_ending(4)
ll2.insert_at_ending(8)
ll = LinkedList()
ll.head = add(ll1.head, ll2.head)
ll.print_list()