STD_5.py

class Node:
    def __init__(self, dataval = None):
        self.dataval = dataval                                              #assigning the data values
        self.nextval = None                                                 #assinging an empty value to the next

class SLinkedList:
    def __init__(self):
        self.headval = None                                                 #assigning an empty value to the head value

    def listprint(self):
        printval = self.headval                                             #creating a print value of the head value
        while printval is not None:                                         #while loop if the print value isn't empty
            print (printval.dataval)                                        #printing the value
            printval = printval.nextval                                     #assing the print value to the next value

    def AtEnd(self, newdata):
        NewNode = Node(newdata)                                             #creating a new node
        if self.headval is None:                                            #if the head value is empty
            self.headval = NewNode                                          #head value is assinged to the new node
            return
        last = self.headval                                                 #last value is assigned to the head value
        while(last.nextval):                                                #while loop of the next value
            last = last.nextval                                             #last value is assigned to the head value
        last.nextval = NewNode                                              #next value is assinged to the new node

    def Insert(self, val_before, newdata):
        if val_before is None:                                              #if the before value is empty
            print("No node to insert after")                                #error message for no node
            return
        else:
            NewNode = Node(newdata)                                         #new variable with the location
            NewNode.nextval = val_before.nextval                            #assign NewNode to the value of the previous value
            val_before.nextval = NewNode                                    #assign the previous value to the new node

list = SLinkedList()                                                        #creating the list
list.headval = Node("Mon")                                                  #starting the list

e2 = Node("Tue")                                                            #creating variables for the lists to link
e3 = Node("Thur")
e4 = Node("Fri")
e5 = Node("Sat")
list.headval.nextval = e2                                                   #listing the next values
e2.nextval = e3
e3.nextval = e4
e4.nextval = e5


list.AtEnd("Sun")                                                           #ending the list
list.Insert(list.headval.nextval, "Wed")                                    #adding Wed as a value
list.listprint()                                                            #printing the list