[LeetCode] Merge Two Sorted Lists

Merge Two Sorted Lists

Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.

解题思路：

这道题是我做的leetcode最容易的题目了。其中有个小技巧，就是在最开始的时候申请一个头结点，然后在融合之后再删除头结点。这样能够让代码更加清晰。利用原有的空间，更加加快了效率，在leetcode跑的时间仅仅13ms。Talk is cheap, show you the cade:

/** * Definition for singly-linked list. * struct ListNode { *     int val; *     ListNode *next; *     ListNode(int x) : val(x), next(NULL) {} * }; */class Solution {public:    ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {        ListNode* head=new ListNode(0);        ListNode* p = head;       //指向融合的最后一个元素        while(l1!=NULL&&l2!=NULL){            if(l1->val<l2->val){                p->next=l1;                p=l1;                l1=l1->next;            }else{                p->next=l2;                p=l2;                l2=l2->next;            }        }        while(l1!=NULL){            p->next=l1;            p=l1;            l1=l1->next;        }        while(l2!=NULL){            p->next=l2;            p=l2;            l2=l2->next;        }        p->next = NULL;        p=head;        head=head->next;        delete p;        return head;    }};