gistfile1.txt

class Element:
    def __init__(self, el=None, nextel=None):
        self.el = el
        self.next_el = nextel


class ListForward:
    def __init__(self):
        self.first = None
        self.last = None
        self.leng = 0
    
    def is_empty(self):
        if self.first == None:
            return True
        else:
            return False
    
    def __repr__(self):
        lst = []
        ell = self.first
        lst = [ell.el]
        while ell.next_el != None:
            ell = ell.next_el
            lst.append(ell.el)
        return f'List: {lst}'
        
    def add(self, n, where=None):
        if type(where) == int:
            if 1 <= where < self.leng: # добавление n-ого элемента по номеру
                self.leng += 1
                current = self.first
                for _ in range (1,where):
                    current = current.next_el
                new = Element(n)
                new.next_el = current.next_el
                current.next_el = new
                    
            elif where == 0: # добавление первого элемента по номеру
                self.leng += 1
                if self.first == None:
                    self.first = Element(n, None)
                    self.last = self.first
                elif self.last == self.first:
                    self.first = Element(n, self.last)
                else:
                    new = Element(n, self.first)
                    self.first = new
                
            elif where == self.leng: #добавление последнего элемента по номеру
                self.leng += 1
                if self.first == None:
                    self.first = Element(n, None)
                    self.last = self.first
                elif self.last == self.first:
                    self.last = Element(n, None)
                    self.first.next_el = self.last
                else:
                    current = Element(n, None)
                    self.last.next_el = current
                    self.last = current
                
            else:
                print(f'POSITION IS OUT OF RANGE. (selected position: {where}, length of list: {self.leng})')
                
        elif where == None or where == 'last': # добавление последнего элемента по слову
            self.leng += 1
            if self.first == None:
                self.first = Element(n, None)
                self.last = self.first
            elif self.last == self.first:
                self.last = Element(n, None)
                self.first.next_el = self.last
            else:
                current = Element(n, None)
                self.last.next_el = current
                self.last = current
                
        elif where == 'first': # добавление первого элемента по слову
            self.leng += 1
            if self.first == None:
                self.first = Element(n, None)
                self.last = self.first
            elif self.last == self.first:
                self.first = Element(n, self.last)
            else:
                new = Element(n, self.first)
                self.first = new
    
    def without_first(self):
        self.first = self.first.next_el
        
    def get_first(self):
        return self.first.el
    
    def length(self):
        return self.leng
    
    def delete_last(self):
        current = self.first
        for _ in range (1, self.leng-1):
            current = current.next_el
        current.next_el = None
        self.last = current
        self.leng -= 1
    
    def get(self, n):
        current = self.first
        for _ in range (1, n):
            current = current.next_el
        return f'Chosen element №{n}: {current.el}'




class Element2:
    def __init__(self, el=None, previous_el=None, nextel=None):
        self.el = el
        self.previous_el = previous_el
        self.next_el = next_el


class List2:
    def __init__(self):
        self.first = None
        self.last = None
        self.leng = 0
    
    def is_empty(self):
        if self.leng == 0:
            return True
        else:
            return False
    
    def __repr__(self):
        lst = []
        ell = self.first
        lst = [ell.el]
        while ell.next_el != None:
            ell = ell.next_el
            lst.append(ell.el)
        return f'List: {lst}'
        
    def add(self, n, where=None):
        if type(where) == int:
            if 1 <= where < self.leng: # добавление n-ого элемента по номеру
                self.leng += 1
                current = self.first
                for _ in range (1,where):
                    current = current.next_el
                new = Element(n)
                new.previous_el = current.previous_el
                new.next_el = current.next_el
                current.next_el.previous_el = new
                current.next_el = new
                    
            elif where == 0: # добавление первого элемента по номеру
                self.leng += 1
                if self.first == None:
                    self.first = Element(n, None, None)
                    self.last = self.first
                elif self.last == self.first:
                    self.first = Element(n, None, self.last)
                    self.last.previous_el = self.first
                else:
                    new = Element(n, None, self.first)
                    self.first.previos_el = new
                    self.first = new
                
            elif where == self.leng: #добавление последнего элемента по номеру
                self.leng += 1
                if self.first == None:
                    self.first = Element(n, None, None)
                    self.last = self.first
                elif self.last == self.first:
                    self.last = Element(n, self.first, None)
                    self.first.next_el = self.last
                else:
                    new = Element(n, self.last_el, None)
                    self.last.next_el = new
                    self.last = new
                    
            else:
                print(f'POSITION IS OUT OF RANGE. (selected position: {where}, length of list: {self.leng})')
                
        elif where == None or where == 'last': # добавление последнего элемента по слову
            self.leng += 1
            if self.first == None:
                self.first = Element(n, None, None)
                self.last = self.first
            elif self.last == self.first:
                self.last = Element(n, self.first, None)
                self.first.next_el = self.last
            else:
                new = Element(n, self.last_el, None)
                self.last.next_el = new
                self.last = new
                
        elif where == 'first': # добавление первого элемента по слову
            self.leng += 1
            if self.first == None:
                self.first = Element(n, None, None)
                self.last = self.first
            elif self.last == self.first:
                self.first = Element(n, None, self.last)
                self.last.previous_el = self.first
            else:
                new = Element(n, None, self.first)
                self.first.previos_el = new
                self.first = new
    
    def without_first(self):
        self.first = self.first.next_el
        self.first.previous_el = None
        
    def get_first(self):
        return self.first.el
    
    def length(self):
        return self.leng
    
    def delete_last(self):
        current = self.first
        for _ in range (1, self.leng-1):
            current = current.next_el
        current.next_el = None
        self.last = current
    
    def get(self, n):
        current = self.first
        for _ in range (1, n):
            current = current.next_el
        return f'Chosen element №{n}: {current.el}'

thank you!