21.合并两个有序链表
链接:LeetCode21.合并两个有序链表
为了方便解题,需要设置一个虚拟头结点
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode() : val(0), next(nullptr) {}
* ListNode(int x) : val(x), next(nullptr) {}
* ListNode(int x, ListNode *next) : val(x), next(next) {}
* };
*/
class Solution {
public:
ListNode* mergeTwoLists(ListNode* list1, ListNode* list2) {
//虚拟头结点
ListNode *listnode = new ListNode();
ListNode *node = listnode;
ListNode *l1=list1,*l2=list2;
while(l1&&l2){
if(l1->val<=l2->val) {node->next=l1;l1=l1->next;}
else {node->next=l2;l2=l2->next;}
node = node->next;
}
if(l1) node->next = l1;
if(l2) node->next= l2;
return listnode->next;
}
};