python heapq custom sort code example
Example: heapq python how to use comparator
class Solution:
def mergeKLists(self, lists: List[ListNode]) -> ListNode:
setattr(ListNode, "__lt__", lambda self, other: self.val <= other.val)
pq = []
for l in lists:
if l:
heapq.heappush(pq, l)
out = ListNode(None)
head = out
while pq:
l = heapq.heappop(pq)
head.next = l
head = head.next
if l and l.next:
heapq.heappush( pq, l.next)
return out.next