21. Merge Two Sorted Lists

LeetCode
,

Dummy Node and Two Pointers (My Solution)

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class Solution {
    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {

        ListNode cur1 = list1;
        ListNode cur2 = list2;

        ListNode dummy = new ListNode(0);
        ListNode cur = dummy;
        while(cur1 != null && cur2 != null){
            if (cur1.val > cur2.val){
                cur.next = cur2;
                cur2 = cur2.next;
            } else {
                cur.next = cur1;
                cur1 = cur1.next;
            }
            cur = cur.next;
        }

        if (cur1 != null){
            cur.next = cur1;
        } else if (cur2 != null){
            cur.next = cur2;
        }

        return dummy.next;
    }
}

Remarks:

  1. don’t forget to connect the remaining nodes of cur1 or cur2