Daily Interview Puzzle: Intersection of Linked Lists

Hi, here's your problem today. This problem was recently asked by Apple:

You are given two singly linked lists. The lists intersect at some node. Find, and return the node. Note: the lists are non-cyclical.

Example:

A = 1 -> 2 -> 3 -> 4

B = 6 -> 3 -> 4

This should return 3 (you may assume that any nodes with the same value are the same node).

Here is a starting point:

def intersection(a, b):

  # fill this in.



class Node(object):

  def __init__(self, val):

    self.val = val

    self.next = None

  def prettyPrint(self):

    c = self

    while c:

      print c.val,

      c = c.next



a = Node(1)

a.next = Node(2)

a.next.next = Node(3)

a.next.next.next = Node(4)



b = Node(6)

b.next = a.next.next



c = intersection(a, b)

c.prettyPrint()

# 3 4