LeetCode 「简单」21.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
输入：l1 = [1,2,4], l2 = [1,3,4]
输出：[1,1,2,3,4,4]
输入：l1 = [], l2 = []
输出：[]
输入：l1 = [], l2 = [0]
输出：[0]
解答
Code
/**
* Definition for singly-linked list.
* function ListNode(val, next) {
* this.val = (val===undefined ? 0 : val)
* this.next = (next===undefined ? null : next)
* }
*/
/**
* @param {ListNode} list1
* @param {ListNode} list2
* @return {ListNode}
*/
var mergeTwoLists = function(list1, list2) {
const prehead = new ListNode(-1);
let cur = prehead;
let p1 = list1, p2 = list2;
while (p1 || p2) {
if (!p1) {
cur.next = p2;
p2 = p2.next;
} else if (!p2) {
cur.next = p1;
p1 = p1.next;
} else if (p1.val > p2.val) {
cur.next = p2;
p2 = p2.next;
} else {
cur.next = p1;
p1 = p1.next;
}
cur = cur.next;
}
return prehead.next;
};