LeetCode21. Merge Two Sorted Lists

LeetCode21. Merge Two Sorted Lists

原地址

题目描述

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.

思路

代码实现

/**
* 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) {
//链表为空
if(l1==NULL || l2==NULL)
{
if(l1==NULL)
return l2;
if(l2==NULL)
return l1;
}

//确定新链表头结点
ListNode* newhead=new ListNode(0);
ListNode* p3;
p3=newhead;

while(l1 && l2){
ListNode* tmp=new ListNode(0);
if(l1->val<=l2->val){
tmp->val=l1->val;
p3->next=tmp;
p3=tmp;
l1=l1->next;
}
else if(l1->val>l2->val){
tmp->val=l2->val;
p3->next=tmp;
p3=tmp;
l2=l2->next;
}

}

//剩余结点
while(l1){
ListNode* tmp=new ListNode(0);
tmp->val=l1->val;
p3->next=tmp;
p3=tmp;
l1=l1->next;
}
while(l2){
ListNode* tmp=new ListNode(0);
tmp->val=l2->val;
p3->next=tmp;
p3=tmp;
l2=l2->next;
}
newhead = newhead->next;
return newhead;
}
};

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