package com.zerroi.leetcode.Three23;

public class MergeTwoLists {
    public static void main(String[] args) {
        ListNode l1 = new ListNode(1, new ListNode(2, new ListNode(4)));
        ListNode l2 = new ListNode(1, new ListNode(3, new ListNode(4)));
        SolutionSecond solutionSecond = new SolutionSecond();
        solutionSecond.mergeTwoLists(l1, l2);
    }
}
class SolutionSecond {
    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
        if (list1 == null || list2 == null) {
            return list1 == null ? list2 : list1;
        }
        ListNode pre = new ListNode(-1);
        ListNode cur = pre;
        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;
            if (list1 == null) {
                cur.next = list2;
            }
            if (list2 == null) {
                cur.next = list1;
            }
        }
        return pre.next;
    }
}