Merge Two Sorted Lists

Merge Two Sorted Lists

 Total Accepted: 4404 Total Submissions: 13615My Submissions

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.

略有提升, 甚是欢喜~

/**
 * 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) 
    {
        if(!l1) return l2;
        if(!l2) return l1;
        ListNode *p, *q;
        ListNode *head = NULL;
        ListNode *tail = NULL;
        p = l1;
        q = l2;
        while(p&&q)
        {
            if(p->val < q->val)
            {
               if(!head)
               {
                   head = p;
                   tail = p;
                   p = p->next;
                
               }
               else
               {
                   tail->next = p;
                   p = p->next;
                   tail = tail->next;
               }
            }
              else
              {
                 if(!head)
                 {
                      head = q;
                      tail = q;
                      q = q->next;
                     
                     
                 }
                else
                {
                   tail->next = q;
                   q = q->next;
                   tail = tail->next;
                   
                }
             }
         }
        if(!p)
        {
            tail->next = q;
        }
        if(!q)
        {
            tail->next = p;
        }
        return head;
    }
};