Question

In python I want to create a singular function that takes two parameters 'head; and 'skip'.

Head is a linked list. Skip is a non negative value. If skip is zero it should return head unchanged. The skip amount determines the amount to skip over. I want to change the linked list accordingly.

If you have a linked list 11 -> 12 -> 18 -> 20 -> 24 -> 32 -> 38 -> 44

and skip =2, then you should return the following:

18 -> 32

If skip = 1, then you should return the following:

12 -> 20 -> 32 -> 44

Answer 1

class ListNode:

    """ Models a single node in a singly-linked list. Has no methods, other

        than the constructor.

    """

    def __init__(self, val):

        """ Constructs the object; caller must pass a value, which will be

            stored in the 'val' field.

        """

        self.val = val

        self.next = None

    def __str__(self):

        vals = []

        objs = set()

        curr = self

        while curr is not None:

            curr_str = str(curr.val)

            if curr in objs:

                vals.append(

                    "{} -> ... (to infinity and beyond)".format(curr_str))

                break

            else:

                vals.append(curr_str)

                objs.add(curr)

            curr = curr.next

        return " -> ".join(vals)

def accordion_n(head,skip_amt):

    if skip_amt<0:

        print("INVALID... skip amount should be non-negative")

        

    elif skip_amt==0:

        return head

    

    else:

        op=[]

        curr_skip=0

        for i in range(len(head)):

            if curr_skip==2:

                op.append(head[i])

                curr_skip=0

            else:

                curr_skip+=1

        return " -> ".join(op)

if __name__=="__main__":

    n=int(input("Enter number of nodes in linked list: "))

    l=[]

    a=int(input())

    l.append(ListNode(a))

    for i in range(1,n):

        a=int(input())

        l.append(ListNode(a))

        l[i-1].next=l[i]

    

    x=str(l[0])

    y = x.split(" -> ")

    

    #Test Case 1

    skip_amt=int(input("Enter skip amount: "))

    print("Given List:",str(l[0]))

    print("Skip amount:",skip_amt)

    ans=accordion_n(y,skip_amt)

    print("Output List:",ans)

#SAMPLE OUTPUT

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