LeetCode OJ:Merge k Sorted Lists

Merge k Sorted Lists

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

算法思想：

每次从lists中找一个值最小的加到链中，最小的那个项指向它的下一个节点

/**
* Definition for singly-linked list.
* struct ListNode {
*     int val;
*     ListNode *next;
*     ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode *mergeKLists(vector<ListNode *> &lists) {
ListNode *nh=new ListNode(0);
ListNode *pre=nh;
while(true){
int minval=INT_MAX;
int index;
for(int i=0;i<lists.size();i++){
if(lists[i]&&lists[i]->val<minval){
index=i;
minval=lists[i]->val;
}
}
if(minval==INT_MAX)break;
pre->next=lists[index];
pre=pre->next;
lists[index]=lists[index]->next;
}
pre->next=NULL;
return nh->next;
}
};