def append(self, item, number_of_columns=0):
"""Insert the given item at the tail of this linked list.
TODO: Running time: O(1) Why and under what conditions?"""
# TODO: Create new node to hold given item
node = Node(item)
if type(item) is list:
node.data = LinkedList(node.data)
# TODO: Append node after tail, if it exists
if self.tail is None:
self.head = node
self.tail = node
else:
self.tail.next = node
self.tail = node
else:
# start from first column
columns = 0
for node in self:
if columns == number_of_columns:
linkedlist = node.data
linkedlist.append(item)
break
else:
# count columns
columns += 1
def test_get_at(self):
n = Node(1)
ll = Linkedlist()
ll.insert_at(0, n)
self.assertEqual(ll.get_at(0), n)
n = Node(2)
ll.insert_at(10, n)
self.assertEqual(ll.get_at(1), n)
def setUp(self):
self.head = Node(1)
self.head.next = Node(3)
self.head.next.next = Node(1)
self.head2 = Node(0)
self.head3 = None
def Push(self, val):
if self.head == None:
self.head = Node(val, None)
else:
cur = self.head
while cur.next != None:
cur = cur.next
cur.next = Node(val, None)
def test_remove_at(self):
n1 = Node(1)
ll = Linkedlist()
self.assertEqual(ll.remove_at(0), None)
ll.insert_at(0, n1)
n2 = Node(2)
ll.insert_at(10, n2)
n3 = Node(3)
ll.insert_at(1, n3)
self.assertEqual(ll.remove_at(2), n3)
self.assertEqual(ll.remove_at(0), n1)
def add(linked1, linked2):
c = 0
head = last = Node(0)
for a, b in zip_longest(linked1, linked2, fillvalue=0):
c += a + b
last.next = Node(c % 10)
last = last.next
c //= 10
if c:
last.next = Node(c)
return head.next
def test_remove_last(self):
n = Node(1)
ll = Linkedlist()
self.assertEqual(ll.remove_last(), None)
ll.insert_last(n)
self.assertEqual(ll.remove_last(), n)
self.assertEqual(ll.size, 0)
n = Node(2)
ll.insert_last(n)
n = Node(3)
ll.insert_last(n)
self.assertEqual(ll.remove_last(), n)
def test_prepend_many(self):
head = Node(5)
linked = LinkedList(head)
linked.prepend(7)
linked.prepend(9)
linked.prepend(11)
self.assertEqual(str(linked), '11->9->7->5', 'should be 11->9->7->5')
def test_append_many(self):
head = Node(5)
linked = LinkedList(head)
linked.append(7)
linked.append(9)
linked.append(11)
self.assertEqual(str(linked), '5->7->9->11', 'should be 5->7->9->11')
def test_remove_not_exisiting(self):
head = Node(5)
linked = LinkedList(head)
linked.append(9)
node = linked.remove(7)
self.assertEqual(node, None, 'should be None')
self.assertEqual(str(linked), '5->9', 'should be 5->9')
def tranverse(node):
nonlocal rst #capture the variable rst
if node is None:
return
tranverse(node.right)
rst = Node(node.data, rst) #append the result
tranverse(node.left)
# Separate the pointers by k-1.
for i in xrange(k-1):
runner = runner.next_node
# Went off the edge: list isn't long enough.
if not runner: return -1
# When runner goes off the end, we know curr is the kth node from the end.
while runner:
curr = curr.next_node
runner = runner.next_node
return curr.data
t1 = Node('a')
t1.next_node = Node('b')
t1.next_node.next_node = Node('c')
t1b = Node('a')
t1b.next_node = Node('b')
t1b.next_node.next_node = Node('c')
print kth_to_last(t1, 2)
print "should be b"
print kth_to_last(t1b, 2)
print "one pass, should be b"
t2 = Node('a')
t2.next_node = Node('b')
if not head.next_node: return head
curr, runner = head, head.next_node
while curr:
runner = curr
while runner.next_node:
if curr.data == runner.next_node.data:
runner.next_node = runner.next_node.next_node
else:
runner = runner.next_node
curr = curr.next_node
# a, a, b | a, b, b, a
t1 = Node('a')
t1.next_node = Node('a')
t1.next_node.next_node = Node('b')
t11 = Node('a')
t11.next_node = Node('a')
t11.next_node.next_node = Node('b')
t2 = Node('a')
t2.next_node = Node('b')
t2.next_node.next_node = Node('b')
t2.next_node.next_node.next_node = Node('a')
t21 = Node('a')
t21.next_node = Node('b')
t21.next_node.next_node = Node('b')
from linkedlist import Node, print_list_from_node
def remove_middle(node):
node.value = node.next.value
node.next = node.next.next
node1 = Node(1)
node2 = Node(2)
node3 = Node(3)
node4 = Node(4)
node5 = Node(5)
node1.next = node2
node2.next = node3
node3.next = node4
node4.next = node5
print_list_from_node(node1)
remove_middle(node3)
print_list_from_node(node1)
from linkedlist import Node linkedlist = Node(1,Node(2,Node(3,Node(4,None)))) linkedlist = Node(1,Node(2,Node(3,Node(1,None)))) print linkedlist.isCircular()
def insertFirst(theList,data): node = Node(data) node.next = theList.first theList.first = node
# Let k be the size of the cycle. Let the hare be exactly k steps
# in front of the tortoise, and move both one step at a time. When
# the tortoise gets to the first node in the cycle the hare will
# also be there because N + k = N for every N in the
# cycle. Since they cannot meet before the cycle, the first place
# they meet is the beginning of the cycle
tortoise = node
hare = node
for i in range(size):
hare = hare.next
while True:
if hare == tortoise:
return hare
hare = hare.next
tortoise = tortoise.next
n1 = Node(1)
n2 = Node(2)
n3 = Node(3)
n4 = Node(4)
n5 = Node(5)
n1.next = n2
n2.next = n3
n3.next = n4
n4.next = n5
n5.next = n3
print find_first_in_loop(n3)