DATA STRUCTURES IN PYTHON DLL
PLEASE DO NOT COPY AND PASTE FROM PREVIOUS CHEGG ANSWERS I'VE
CHECKED THEM ALL THEY'RE WRONG
DO NOT USE ANY OTHER DATA STRUCTURE THAN DLL (MEANING NO LISTS,
DICTIONARIES)
PLEASE ADD THE FUNCTIONS TO THE CODE AND MAKE SURE IT RUNS
#CODE
class DLL:
class _Node:
def __init__(self, data, next=None, prev=None):
self._data = data
self._next = next
self._prev = prev
def __str__(self):
return '({0})'.format(self._data)
def __init__(self):
self._h = None
self._t = None
self._size = 0
def __str__(self):
st = "List=<"
curr = self._h
while curr is not None:
st = st + str(curr._data)
# st = st + str(curr)
if curr._next is not None:
st = st + ","
curr = curr._next
return st+">"
def __contains__(self, val):
curr = self._h
while curr is not None:
if curr._data == val:
return True
curr = curr._next
return False
def isEmpty(self):
return self._h is None
def headNode(self):
return self._h
def tailNode(self):
return self._t
def head_val(self):
if not self.isEmpty():
return self._h._data
else:
raise TypeError("None value")
def tail_val(self):
if not self.isEmpty():
return self._t._data
else:
raise TypeError("None value")
def printF(self):
p = self._h
while p is not None:
print(p._data, end=",")
p = p._next
print()
def printR(self):
p = self._t
while p is not None:
print(p._data, end=",")
p = p._prev
print()
def addToHead(self, data):
newNode = self._Node(data, self._h, None)
if self._h is not None:
self._h._prev = newNode
self._h = newNode
if self._t is None:
self._t = self._h
self._size += 1
def addToTail(self, data):
newNode = self._Node(data, None, self._t)
if self._t is not None:
self._t._next = newNode
self._t = newNode
if self._h is None:
self._h = newNode
self._size += 1
def removeHead(self):
if self.isEmpty():
raise TypeError("Empty")
if self._h == self._t: # one Node
self._h = self._t = None
else:
self._h = self._h._next
self._h._prev = None
self._size -= 1
def removeTail(self):
if self.isEmpty():
raise TypeError("Empty")
if self._h == self._t: # one Node
self._h = self._t = None
else:
self._t = self._t._prev
self._t._next = None
self._size -= 1
def clear(self):
self._h = self._t = None
self._size = 0
def remove(self, val):
if self.isEmpty():
return False
if self._h._data == val:
self.removeHead()
return True
# if self._h == self._t: # one Node
# return False
curr = self._h #._next
while curr._next is not None:
if curr._data == val:
curr._prev._next = curr._next
curr._next._prev = curr._prev
self._size -= 1
return True
curr = curr._next
if self._t._data == val:
self.removeTail()
return True
return False
def __len__(self):
return self._size
def __setitem__(self, k, val):
if k < 0:
raise IndexError("Index error < 0")
if k >= self._size:
raise IndexError("Index error > len")
curr = self._h
c = 0
while curr is not None:
if c == k:
curr._data = val
return
else:
c += 1
curr = curr._next
def __getitem__(self, k):
if k < 0:
raise IndexError("Index error < 0")
if k >= self._size:
raise IndexError("Index error > len")
curr = self._h
c.
DATA STRUCTURES IN PYTHON DLLPLEASE DO NOT COPY AND PASTE FROM PRE.pdf
1. DATA STRUCTURES IN PYTHON DLL
PLEASE DO NOT COPY AND PASTE FROM PREVIOUS CHEGG ANSWERS I'VE
CHECKED THEM ALL THEY'RE WRONG
DO NOT USE ANY OTHER DATA STRUCTURE THAN DLL (MEANING NO LISTS,
DICTIONARIES)
PLEASE ADD THE FUNCTIONS TO THE CODE AND MAKE SURE IT RUNS
#CODE
class DLL:
class _Node:
def __init__(self, data, next=None, prev=None):
self._data = data
self._next = next
self._prev = prev
def __str__(self):
return '({0})'.format(self._data)
def __init__(self):
self._h = None
self._t = None
self._size = 0
def __str__(self):
st = "List=<"
curr = self._h
while curr is not None:
st = st + str(curr._data)
# st = st + str(curr)
if curr._next is not None:
st = st + ","
curr = curr._next
return st+">"
def __contains__(self, val):
curr = self._h
while curr is not None:
if curr._data == val:
2. return True
curr = curr._next
return False
def isEmpty(self):
return self._h is None
def headNode(self):
return self._h
def tailNode(self):
return self._t
def head_val(self):
if not self.isEmpty():
return self._h._data
else:
raise TypeError("None value")
def tail_val(self):
if not self.isEmpty():
return self._t._data
else:
raise TypeError("None value")
def printF(self):
p = self._h
while p is not None:
print(p._data, end=",")
p = p._next
print()
def printR(self):
p = self._t
while p is not None:
print(p._data, end=",")
p = p._prev
print()
def addToHead(self, data):
newNode = self._Node(data, self._h, None)
if self._h is not None:
self._h._prev = newNode
self._h = newNode
3. if self._t is None:
self._t = self._h
self._size += 1
def addToTail(self, data):
newNode = self._Node(data, None, self._t)
if self._t is not None:
self._t._next = newNode
self._t = newNode
if self._h is None:
self._h = newNode
self._size += 1
def removeHead(self):
if self.isEmpty():
raise TypeError("Empty")
if self._h == self._t: # one Node
self._h = self._t = None
else:
self._h = self._h._next
self._h._prev = None
self._size -= 1
def removeTail(self):
if self.isEmpty():
raise TypeError("Empty")
if self._h == self._t: # one Node
self._h = self._t = None
else:
self._t = self._t._prev
self._t._next = None
self._size -= 1
def clear(self):
self._h = self._t = None
self._size = 0
def remove(self, val):
if self.isEmpty():
return False
if self._h._data == val:
4. self.removeHead()
return True
# if self._h == self._t: # one Node
# return False
curr = self._h #._next
while curr._next is not None:
if curr._data == val:
curr._prev._next = curr._next
curr._next._prev = curr._prev
self._size -= 1
return True
curr = curr._next
if self._t._data == val:
self.removeTail()
return True
return False
def __len__(self):
return self._size
def __setitem__(self, k, val):
if k < 0:
raise IndexError("Index error < 0")
if k >= self._size:
raise IndexError("Index error > len")
curr = self._h
c = 0
while curr is not None:
if c == k:
curr._data = val
return
else:
c += 1
curr = curr._next
def __getitem__(self, k):
if k < 0:
raise IndexError("Index error < 0")
if k >= self._size:
5. raise IndexError("Index error > len")
curr = self._h
c = 0
while curr is not None:
if c == k:
return curr._data
else:
c += 1
curr = curr._next
def __delitem__(self, k):
if k < 0:
# raise IndexError("Index error < 0")
print("Index error")
return
if self.isEmpty():
return
if k == 0:
self.removeHead()
return
if k == self._size-1:
self.removeTail()
return
if k >= self._size:
# raise IndexError("Index > len")
print("Index error")
return
curr = self._h
c = 0
while curr._next is not None:
if c == k:
curr._prev._next = curr._next
curr._next._prev = curr._prev
self._size -= 1
return
else:
c += 1
6. curr = curr._next
# This function should be used in sorted list only
def insert(self, data):
if self.isEmpty() or data <= self._h._data:
self.addToHead(data)
return
if data >= self._t._data:
self.addToTail(data)
return
curr = self._h._next
while curr is not None:
if data <= curr._data:
newnode = self._Node(data, curr, curr._prev)
curr._prev._next = newnode
curr._prev = newnode
self._size += 1
return
else:
curr = curr._next
def extend(self, other):
curr = other._h
while curr is not None:
self.addToTail(curr._data)
curr = curr._next
def copy(self): # shallow copy
other = DLL()
# e is the result of self[];
# i.e. the result of getitem function
# for e in self:
# other.addToTail(e)
curr = self._h
while curr is not None:
other.addToTail(curr._data)
curr = curr._next
return other Ex1. Append Reverse (20 points) - Write the implementation of a member-
function appendReverse(self), which appends the current list in reverse order to the end of the
7. current list. This should be done in O(n). - Example: Assume that the current list =1,2,1,4,1,5 0
The function should change the current list to =1,2,1,4,1,5,5,1,4,1,2,1 Ex2. Accumulative Count
(20 points) - Write the most efficient implementation of the member-function acumCount(self),
which prints how long this current element exists in the remaining elements after the current
element. - Example: Assume that the current list =<1,2,1,4,1,4,2,5,2; then the output is
1:2<1,2,1,4,1,4,2,5,2>2:21,2,1,4,1,4,2,5,21:14:11:04:02:15:02:0
