Question

i need to create methods that:

append_element(self, val) This method should increase the size of the list by one, adding the specified value in the new tail position. This is the only way to add a value as the tail.

insert_element_at(self, val, index) If the provided index identifies a valid zero-based position within the list, then insert the specified value at that position, increasing the length by one. This method can be used to insert at the head of a non-empty list, but cannot append to a list. The provided index must be within the current bounds of the list. If the index is not valid, raise an IndexError exception.

remove_element_at(self, index) If the provided index identifies a valid zero-based position within the list, then remove and return the value stored in a Node at that position. If the index is not valid, raise an IndexError exception.

get_element_at(self, index) If the provided index identifies a valid zero-based position within the list, then obtain the value from the Node at that position and return it. Do not unlink the Node object. If the index is not valid, raise an IndexError exception.

class Linked_List:

class __Node:

def __init__(self, val):

# declare and initialize the private attributes

# for objects of the Node class.

# TODO replace pass with your implementation

pass

def __init__(self):

# declare and initialize the private attributes

# for objects of the sentineled Linked_List class

# TODO replace pass with your implementation

pass

def __len__(self):

# return the number of value-containing nodes in

# this list.

# TODO replace pass with your implementation

pass

def append_element(self, val):

# increase the size of the list by one, and add a

# node containing val at the new tail position. this

# is the only way to add items at the tail position.

# TODO replace pass with your implementation

pass

this is python

Answer 1

python code is listed as part of screenshot Linked_List_python_code_part1.jpg to Linked_List_python_code_part4.jpg  

Execution status ;

screenshots Linked_List_execution_part1.jpg and LInked_List_execution_part2.jpg

All the methods are called and tested in the main with comments

Pclass Linked_List : class_Node : def __init__(self, val) : self. data = val self.next = None def __init__(self): self. top = None H HNL 000000000 HHNNNNNN def len_(self) : j = 0 if self. top != None : i = self.top else: return o while( i != None ): i = i.next j = 1 + 1 return j E En") def_print__(self): i = self.top print("\n == while ( i != None ) : print("Val : ", i.data) i = i.next print("\n \n") def append_element (self,val): n = Linked_List. Node (val) 38 Srith NOO if (self. top == None) : #print ("Top is None \n") self. top = n lse: t = self.top #print("Top is nbNone \n") while ( t.next != None ) : t = t.next t.next = n

def insert element at (self, val, index): N O inn 1 h CO if ( index >= 0 ) & ( index < self. len ( ) : #print ("Inserting element at ", index,"\n") 0 nl = Linked_List. _Node (val) prev = None cur = self.top while (cur != None) : #print(" prev, cur, ", cur data, "", ,"", index," \n") if j == index: print(" j == index exchanging links \n") if prev != None : prev.next = nl else: nl.next = self.top self. top = ni nl.next = cur prev = cur cur = cur.next j = 3 + 1 else: raise IndexError(' Insert index is out of bounds \n') 0 0 0 0 0 0 POCO oy in NO CON UN - - ] 1 CO CO CO CO CO CO LOCO - UN CO CO COCO def get_element_at (self, index): if ( ( index >= 0 ) & ( index < self._len_())) : j = 0 cur = self.top while ( cur != None ): if (j == index) : return cur.data cur = cur.next j = i + 1 else: raise IndexError(' Insert index is out of bounds \n')

def remove_element_at (self, index): if ( index >= 0 ) & ( index < self. _len_() nl = None ) : 01 O 0 0 0 0 0 0 0 0 0 0 0 OOOOO OO ,"", index," \n") j = 0 prev = None cur = self.top while ( cur != None) : #rint(" prev, cur, j", cur.data, "", if j == index: #print(" j == index exchanging links \n") nl = cur if prev != None : prev.next = cur.next nl.next = None else: self. top = self. top.next 105 107 108 prev = cur cur = cur.next j = j +1 return nl else: raise IndexError('Insert index is out of bounds \n') Qif 116 117 118 119 120 122 name__ == "_main_': # Add Linked List element 11 = Linked_List() ii. _print__() print(" Empty Len : ", 11. _len_0) print("======= il.append_element (2) print(" Data 2 Len:", 11._len_()) 11. __print_o) print("======= 11.append_element (3) print(" 3 Len:", 11._len_()) 11. __print_o) print("===== # Insert Element 11.insert_element_at (5,1) print(" 4 Len : ", 11. _len__0) 11. __print_o print("====== 0 0 0 ω 131 132 134 135

137 138 139 141 Ф Ф DONT 000000 # Catch exception while inserting try: il.insert_element_at (5,3) print(" 4 Len: "; 11. _len_0) 11. _print__() except IndexError as er: print(" Exception catched : ", er ) print("= === # Demo Get element print(" Value at 0", 1l.get_element_at(0); "\n") print(" Value at 1", 11.get_element_at(1), "\n") print(" Value at 2", 11.get element at (2), "\n") # Catch exception when get element throws try : print(" Value at 2", 11.get_element_at(3), "\n") except IndexError as er: print(" Exception catched : ", er ) print (======= # Remove Element demo 11.remove_element_at (1) print(" 4 Len : ", 11. _len_0) 11. print ( print(" = 11.remove_element_at (1) OLD ===\n") 162 = == n" ) ona print(" 4 Len : ", 11._len_0) 11. __print__() print("= # Catch exception while remove element throws exception try : ll.remove_element_at (2) except IndexError as er: print(" Exception catched : ", er )

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