Jianzhi offer 25. Merge two sorted linked lists

Jianzhi offer 25. Merge two sorted linked lists

Title description

Problem-solving ideas

class Solution {
    
    
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
    
    
        //用尾插法，将l1和l2插入到虚节点后面
        ListNode virtualNode = new ListNode(0);
        ListNode rear = virtualNode;

        while (l1 != null && l2 != null) {
    
    
            if (l1.val < l2.val) {
    
    
                rear.next = l1;
                l1 = l1.next;
            } else {
    
    
                rear.next = l2;
                l2 = l2.next;
            }
            rear = rear.next;
            rear.next = null;
        }
        //将剩余的部分直接接上去
        rear.next = (l1 == null) ? l2 : l1;

        return virtualNode.next;
    }
}