class Solution { public ListNode mergeTwoLists(ListNode l1, ListNode l2) { if (l1 == null) { return l2; } else if (l2 == null) { return l1; } else if (l1.val < l2.val) { //计算当前节点,下一节点值得大小 l1.next = mergeTwoLists(l1.next, l2); //返回值后,移动指针 return l1; }…