Challenge: Build and Show a Linked List

Lab Python Beginner 10 points

Read some values, build a linked list from them with a Node class, then print it in the form a -> b -> c -> None followed by the number of nodes on the next line (count them by walking the list).

Input

One line of words or numbers.

Output

a -> b -> ... -> None
Nodes: <count>

Example

Input

3 1 4

Output

3 -> 1 -> 4 -> None
Nodes: 3

Sample input available Sample output available

Editor

Python

Hints

Add nodes to the front while going through the values backwards.

Walk with cur = cur.next until cur is None.

Solution explanation

Walking the list from the head is O(n), one node at a time.

Show solution

class Node:
    def __init__(self, value):
        self.value = value
        self.next = None


values = input().split()
head = None
for v in reversed(values):
    node = Node(v)
    node.next = head
    head = node
parts = []
count = 0
cur = head
while cur:
    parts.append(cur.value)
    count += 1
    cur = cur.next
print(" -> ".join(parts + ["None"]))
print("Nodes:", count)

Output

Answer