[Leetcode][python]Merge k Sorted Lists/合并K个排序链表

class Solution(object):
    def mergeKLists(self, lists):
        """
        :type lists: List[ListNode]
        :rtype: ListNode
        """
        heap = []
        for node in lists:
            if node: 
                heap.append((node.val, node))  # 堆中放入tuple：值，地址
        heapq.heapify(heap)  # 做成堆
        dummy = ListNode(0)
        curr = dummy

        while heap:
            pop = heapq.heappop(heap)  # 从堆中取最小的值
            curr.next = ListNode(pop[0])  # 将值放入
            curr = curr.next
            if pop[1].next:  # 如果该链表没结束
                heapq.heappush(heap, (pop[1].next.val, pop[1].next)) # 将该链表下个节点压入栈中
        return dummy.next