Merge Two Sorted Lists 分类： Leetcode（排序） 2015-04-08 21:59 24人阅读 评论(0) 收藏

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.

/**
 * 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 dummy(-1);
        ListNode *p = &dummy;
        while(l1 &&l2) {
            if(l1->val >= l2->val) {
                p->next = l2;
                p = l2;
                l2 = l2->next;
            }
            else {
                p->next = l1;
                p = l1;
                l1 = l1->next;
            }
        }
        if(l1) p->next = l1;
        else p->next = l2;
        return dummy.next;
        
        
    }
};

 

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