描述
将两个排序链表合并为一个新的排序链表
样例
样例
样例 1:
输入: list1 = null, list2 = 0->3->3->null
输出: 0->3->3->null
样例2:
输入: list1 = 1->3->8->11->15->null, list2 = 2->null
输出: 1->2->3->8->11->15->null
思考
从头部开始比较,把较小的放入到新的链表当中
代码
/**
* Definition of singly-linked-list:
* class ListNode {
* public:
* int val;
* ListNode *next;
* ListNode(int val) {
* this->val = val;
* this->next = NULL;
* }
* }
*/
class Solution {
public:
/**
* @param l1: ListNode l1 is the head of the linked list
* @param l2: ListNode l2 is the head of the linked list
* @return: ListNode head of linked list
*/
ListNode * mergeTwoLists(ListNode * l1, ListNode * l2) {
// write your code here
if (!l1) return l2;
if (!l2) return l1;
ListNode *head;
if (l1->val <= l2->val) {
head = new ListNode(l1->val);
l1 = l1->next;
}
else {
head = new ListNode(l2->val);
l2 = l2->next;
}
ListNode *cur = head;
while (l1 && l2) {
if (l1->val <= l2->val) {
ListNode *temp = new ListNode(l1->val);
cur->next = temp;
cur = cur->next;
l1 = l1->next;
}
else {
ListNode *temp = new ListNode(l2->val);
cur->next = temp;
cur = cur->next;
l2 = l2->next;
}
}
if (!l1) cur->next = l2;
else cur->next = l1;
return head;
}
};