fork(1) download
copy 
  1. # Merge K Sorted Lists (LC version 3.01).
  2.  
  3. from heapq import heappush, heappop
  4.  
  5. # List.
  6.  
  7. class ListNode:
  8.     def __init__(self, val=None, next=None):
  9.         self.val = val
  10.         self.next = next
  11.  
  12. def makeList(seq):
  13.     t = None
  14.     for x in reversed(seq):
  15.         t = ListNode(x, t)
  16.     return t
  17.  
  18. def printList(l):
  19.     a = []
  20.     while l:
  21.         a.append(l.val)
  22.         l = l.next
  23.     print('List(', a, ')', sep='')
  24.  
  25. # Merge.
  26.  
  27. def mergeKLists(lists):
  28.     heap = []
  29.     for k, n in enumerate(lists):
  30.         if n:
  31.             heappush(heap, (n.val, k, n))
  32.     temp = ListNode()
  33.     if heap:
  34.         t = temp
  35.         while True:
  36.             _, k, n = heappop(heap)
  37.             t.next = n
  38.             if not heap:
  39.                 break
  40.             t = t.next
  41.             n = n.next
  42.             if n:
  43.                 heappush(heap, (n.val, k, n))
  44.     return temp.next
  45.  
  46. # Show.
  47.  
  48. l0 = makeList([])
  49. l1 = makeList([1, 3, 5, 7])
  50. l2 = makeList([2, 4, 6])
  51. l3 = makeList([0, 4, 8])
  52.  
  53. printList(l0)
  54. printList(l1)
  55. printList(l2)
  56. printList(l3)
  57.  
  58. printList(mergeKLists([]))
  59. printList(mergeKLists([l0]))
  60. printList(mergeKLists([l1]))
  61. printList(mergeKLists([l1, l2, l3]))
Success #stdin #stdout 0.09s 14116KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
List([])
List([1, 3, 5, 7])
List([2, 4, 6])
List([0, 4, 8])
List([])
List([])
List([1, 3, 5, 7])
List([0, 1, 2, 3, 4, 4, 5, 6, 7, 8])
https://ideone.com/NbzomI
language:
Python 3 (python  3.12)
created:
12 days ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!