Merge two sorted lists

Input two monotonically increasing list, output two list of linked lists, of course, we need to synthesize the linked list to meet the monotone non-reduction rules.

Idea: There can be two methods of implementation, the first is through the recursive implementation, the second is through non-recursive implementation.

 Public classSolution { PublicListNode Merge (listnode list1,listnode list2) {if(List1 = =NULL&& List2 = =NULL){            return NULL; }        if(List1 = =NULL&& list2!=NULL){            returnList2; }        if(list1!=NULL&&list2==NULL){            returnList1; } listnode Merge=NULL; if(List1.val <list2.val) {Merge=List1; Merge.next=Merge (LIST1.NEXT,LIST2); }Else{Merge=List2; Merge.next=Merge (List1,list2.next); }        returnmerge; }}

Non-recursive:

Public ListNode Merge (ListNode list1,listnode list2) {if (List1 = = NULL && List2 = = null) {retur        n null;        } if (List1 = = null && list2!=null) {return list2;        } if (List1!=null&&list2==null) {return list1;        } ListNode merge = null;        ListNode merge2 = null;                    while (List1!=null &&list2!=null) {if (list1.val<list2.val) {if (merge = = null) { Merge2 = merge = List1; //Make sure the head node}else{merge.next = List1;                Merge = Merge.next;            } list1 = List1.next;                }else{if (merge = = null) {merge2 = merge = List2;                    }else{merge.next = List2; Merge = Merge.next;            This also wants to shift} LIST2 = List2.next; }} if (list1!=null) {merge.next = List1;//node assignment can} if (List2!=null) {Mer        Ge.next = List2;    } return merge2; }

　　

Merge two sorted lists