def partition(head, x):
if head == None: return
p1 = head
p2 = head
after = None
while p2 != None:
if p2.get_data() > x:
# copy to after and delete current
if after == None:
after = Node(p2.get_data())
else:
after.append_to_tail(p2.get_data())
# if p2 is head
if p2 == head:
head = head.get_next()
p1 = head
p2 = head
else:
p1.set_next(p2.get_next())
p2 = p2.get_next()
else:
p1 = p2
p2 = p2.get_next()
# append to end
p1.set_next(after)
return head
def add(self, item):
"""add(item) 链表头部添加元素"""
node = Node(item)
if self.is_empty():
self.head = node
return
node.next = self.head
self.head = node
def test(self):
head = Node(0)
for i in range(1, 10):
head.append_to_tail(i)
head.print_all_data()
self.assertEqual(find_kth_last_element2(3, head), 7)
self.assertEqual(find_kth_last_element2(10, head), 0)
self.assertEqual(find_kth_last_element2(12, head), None)
def add(self, item):
"""add(item) 链表头部添加元素"""
node = Node(item)
if self.is_empty():
self.head = node
self.head.next = self.head
return
tmp_node = self.head
while tmp_node.next != self.head:
tmp_node = tmp_node.next
node.next = self.head
tmp_node.next = node
self.head = node
def append(self, item):
""" append(item) 链表尾部添加元素"""
node = Node(item)
# 空节点的时候
if self.is_empty():
self.head = node
# 自己指向自己
self.head.next = self.head
# 单节点的时候
elif self.head.next == self.head:
self.head.next = node
node.next = self.head
else:
tmp_node = self.head
while tmp_node.next != self.head:
tmp_node = tmp_node.next
tmp_node.next = node
node.next = self.head
def insert(self, pos, item):
"""insert(pos, item) 指定位置添加元素"""
node = Node(item)
if pos <= 1:
self.add(node)
elif pos >= self.length():
self.append(node)
else:
count = 1
pre_node = self.head
next_node = self.head
while next_node.next != self.head:
pre_node = next_node
next_node = next_node.next
count += 1
if count == pos:
break
pre_node.next = node
node.next = next_node
def sum_list_recursive(op1, op2, plus=False):
if op1 == None and op2 == None and plus == False:
return None
res = None
value = (1 if plus else 0)
if op1 != None:
value += op1.get_data()
if op2 != None:
value += op2.get_data()
res = Node(value % 10)
if value >= 10:
plus = True
else:
plus = False
# at least one list is not ended --> recurse
if op1 != None or op2 != None:
tail = sum_list_recursive((op1.get_next() if op1 != None else None), (op2.get_next() if op2 != None else None), plus)
res.set_next(tail)
return res
def append(self, item):
""" append(item) 链表尾部添加元素"""
node = Node(item)
# 空节点的时候
if self.is_empty():
self.head = node
# 单节点的时候
elif not self.head.next:
self.head.next = node
else:
tmp_node = self.head
while tmp_node.next:
tmp_node = tmp_node.next
tmp_node.next = node
p1 = head
p2 = head.get_next().get_next()
if p2 == None: return
while p2 != None and p2.get_next() != None:
p2 = p2.get_next().get_next()
p1 = p1.get_next()
p1.set_next(p1.get_next().get_next())
return head
## given only access to that node.
def delete_middle(node):
# copy the next node to current position, then delete next
node.set_data(node.get_next().get_data())
node.set_next(node.get_next().get_next())
# if 'node' is the last one, mark as dummy
#---------------
head = Node(0)
for i in range(1, 9):
head.append_to_tail(i)
head.print_all_data()
print '----------------'
delete_middle(head)
head.print_all_data()