21.合并两个有序链表.java

/*
 * @lc app=leetcode.cn id=21 lang=java
 *
 * [21] 合并两个有序链表
 */

// @lc code=start
/**
 * Definition for singly-linked list.
 * public class ListNode {
 * int val;
 * ListNode next;
 * ListNode() {}
 * ListNode(int val) { this.val = val; }
 * ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */

class Solution {
    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
        ListNode vNode = new ListNode(-1);
        ListNode cur = vNode;

        while (list1 != null && list2 != null) {
            if (list1.val < list2.val) {
                cur.next = list1;
                list1 = list1.next;
            } else {
                cur.next = list2;
                list2 = list2.next;
            }
            cur = cur.next;

        }
        ListNode rest = list1 == null ? list2 : list1;
        while (rest != null) {
            cur.next = rest;
            rest = rest.next;
            cur = cur.next;
        }
        return vNode.next;
    }
}
// @lc code=end