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☕今日份刷题:合并两个有序链表
题目描述:
将两个升序链表合并为一个新的 升序 链表并返回。新链表是通过拼接给定的两个链表的所有节点组成的。
示例1:
cpp
输入:l1 = [1,2,4], l2 = [1,3,4]
输出:[1,1,2,3,4,4]
示例2:
cpp
输入:l1 = [], l2 = []
输出:[]
示例3:
cpp
输入:l1 = [], l2 = [0]
输出:[0]
题目分析:
这题可太经典了,直接取小的尾插
cpp
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* struct ListNode *next;
* };
*/
struct ListNode* mergeTwoLists(struct ListNode* list1, struct ListNode* list2){
if(list1 == NULL)
{
return list2;
}
if(list2 == NULL)
{
return list1;
}
struct ListNode* head = NULL,*tail = NULL;
while(list1 && list2)
{
//取小的尾插
if(list1->val < list2->val)
{
if(tail == NULL)
{
head = tail = list1;
}
else
{
tail->next = list1;
tail = tail->next;
}
list1 = list1->next;
}
else
{
if(tail == NULL)
{
head = tail = list2;
}
else
{
tail->next = list2;
tail = tail->next;
}
list2 = list2->next;
}
}
if(list1)
{
tail->next = list1;
}
if(list2)
{
tail->next = list2;
}
return head;
}