leetcode 23. 合并K个排序链表

class Solution(object):
    def adjust_to_min_heap(self, arr, i, end):
        while i < end:
            l = 2 * i + 1
            r = 2 * i + 2
            min_ind = i
            if l < end and arr[l][0] < arr[min_ind][0]:
                min_ind = l
            if r < end and arr[r][0] < arr[min_ind][0]:
                min_ind = r
            if min_ind == i:
                break
            else:
                arr[min_ind], arr[i] = arr[i], arr[min_ind]
                i = min_ind
        return arr
        
    def mergeKLists(self, lists):
        """
        :type lists: List[ListNode]
        :rtype: ListNode
        """
        if len(lists) == 0:return None
        k = len(lists)
        temp = []
        for i in range(len(lists)):
            if lists[i] == None:
                temp.append((2147483647, -1))
            else:
                temp.append((lists[i].val, i))
        first = (k - 1)/2
        while first >= 0:
            temp = self.adjust_to_min_heap(temp, first, len(temp))
            first -= 1
        res = ListNode('#')
        start = res
        end = len(temp)
        while True:
            cur = temp[0]
            if cur[1] == -1:break
            res.next = ListNode(cur[0])
            lists[cur[1]] = lists[cur[1]].next
            temp[0] = (lists[cur[1]].val, cur[1]) if lists[cur[1]] else (2147483647, -1)
            temp = self.adjust_to_min_heap(temp, 0, end)
            res = res.next
        return start.next