LeetCodeMerge k Sorted Lists

Merge k sorted linked lists and return it as one sorted list. Analyze
and describe its complexity.

对每一个排序链表都设置一个指针。每次讲指针指向的单元中最小值链接，直到所有指针为空。

public class Solution {
   public ListNode
mergeKLists(List<ListNode> lists) {

       

        int length = lists.size();

        if(length == 0)return null;

        int num = 0;

        while(num<length)

        {

           
if(lists.get(num)!=null)

               
break;

            num++;

        }

        if(num == length)return null;

        ListNode[] start = new
ListNode[length];
        int
minIndex = 0;
        int min =
Integer.MAX_VALUE;
        for(int
i=0;i<length;i++)
        {

           
start[i] = lists.get(i);

           
if(start[i]!=null&&start[i].val<min)

            {

               
minIndex = i;

               
min = start[i].val;

            }

        }

        ListNode head =
lists.get(minIndex);
       
ListNode node = head;
       
start[minIndex] = start[minIndex].next;

        while(!isAllEnd(start))

        {

           
findMin(start,node);

            node =
node.next;
        }

       

        return head;

       

       
    }

    public void findMin(ListNode[] lists,ListNode node)

    {
       
int min = Integer.MAX_VALUE;

        int minIndex = 0;

        for(int
i=0;i<lists.length;i++)
       
{
           
if(lists[i]!=null&&lists[i].val<min)

            {

               
min = lists[i].val;

               
minIndex = i;

            }

        }

        node.next = lists[minIndex];

        lists[minIndex] =
lists[minIndex].next;
    }

   
    public boolean
isAllEnd(ListNode[] lists)
    {

        int length = lists.length;

        int i = 0;

        while(i<length)

        {

           
if(lists[i] != null)

            {

               
return false;

            }

            i++;

        }

        return true;

    }
}