leetcode.23合并 k 个排序链表

/**
 * 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) {
        int i,minn,minpos;

        ListNode* s=(ListNode*)malloc(sizeof(ListNode));
        ListNode* p=s;
        s->next=NULL;//这里对于处理空输入很关键
        while(true){
            minn=100000;
            minpos=-1;
        for(i=0;i<lists.size();i++){
            
            if(lists[i]!=NULL&&lists[i]->val<minn){
                minn=lists[i]->val;
                minpos=i;
            }
        }
        if(minpos==-1){
            break;
        }
        p->next=lists[minpos];
        lists[minpos]=lists[minpos]->next;
        p->next->next=NULL;
        p=p->next;
        }
        return s->next;
    }
};