Hi, here's your problem today. This problem was recently asked by Twitter:
You are given an array of k sorted singly linked lists. Merge the linked lists into a single sorted linked list and return it.
Here's your starting point:
class Node(object): def __init__(self, val, next=None): self.val = val self.next = next def __str__(self): c = self answer = "" while c: answer += str(c.val) if c.val else "" c = c.next return answer def merge(lists): # Fill this in. a = Node(1, Node(3, Node(5))) b = Node(2, Node(4, Node(6))) print merge([a, b]) # 123456