Merge sorted lists in python

Question

I have a bunch of sorted lists of objects, and a comparison function

class Obj :
    def __init__(p) :
        self.points = p
def cmp(a, b) :
    return a.p         


        

Answer 1

One line solution using sorted:

def magic(*args):
  return sorted(sum(args,[]), key: lambda x: x.points)

IMO this solution is very readable.

Using heapq module, it could be more efficient, but I have not tested it. You cannot specify cmp/key function in heapq, so you have to implement Obj to be implicitly sorted.

import heapq
def magic(*args):
  h = []
  for a in args:
    heapq.heappush(h,a)
  return [i for i in heapq.heappop(h)