'What is the difference between these two codes? (Python: circular singly linked list)

These are the codes for __iter__ method of a circular singly linked list. But I don't understand the difference between the two.

def __iter__(self):
    node = self.head
    while node:     # i.e. while node is not None
        yield node
        if node.next == self.head:   # i.e. if node.next refers to the first node, i.e. if that is the last node, break
            break       # without this if condition, the loop will loop forever
        node = node.next

and

def __iter__(self):
    node = self.head
    while node:
        yield node
        node = node.next
        if node == self.tail.next:
            break
python-3.xdata-structureslinked-list


Solution 1:[1]

def __iter__(self):
    node = self.head
    while node:     # i.e. while node is not None
        yield node
        if node.next == self.head:   # i.e. if node.next refers to the first node, i.e. if that is the last node, break
            break       # without this if condition, the loop will loop forever
        node = node.next

This if condition doesn't garantee to stop loop over. There is no way node.next is equal to self.head in the above code. However, as the node will update for every iteration, it will stop the iterations when it reachs node==null

def __iter__(self):
    node = self.head
    while node:
        yield node
        node = node.next
        if node == self.tail.next:
            break

** this code is the same as:**

def __iter__(self):
    node = self.head
    while node:
        yield node
        node = node.next
        if node == None:
            break

As node.tail is the last element in the linked list, node.tail.next would be None. node.tail

Sources

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Source: Stack Overflow

Solution Source
Solution 1 Endalew Tesfa

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