Leetcode 合并两个有序链表

java solution

class Solution {
    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
        ListNode dummy = new ListNode(0);
        ListNode current = dummy;

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