Interview question 17: Merge two sorted lists

ListNode Class (Node Class)

1  Packageleetcode.utilities;2 3  Public classListNode {4      Public intVal;5      PublicListNode Next;6      PublicListNode (intval) {7         //TODO auto-generated Constructor stub8          This. val =Val;9          This. Next =NULL ; Ten     }     One     //Print linked list A          Public Static voidprintlist (ListNode head) { -System.out.println ("Prinylist start"); -ListNode Pnode =head; theSystem.out.print ("{"); -              while(Pnode! =NULL){ -System.out.print (Pnode.val + ""); -Pnode=Pnode.next; +             } -System.out.println ("}"); +         } A}

Implement Java code recursively:

1  PackageCom.hb.jzoffer;2 3 ImportLeetcode.utilities.ListNode;4 //question 17: Merging two sorted lists5  Public classmergesortedlists {6      Publiclistnode Merge (ListNode pHead1, ListNode pHead2) {7         //determine if two linked lists are empty8         if(PHead1 = =NULL ){9             returnpHead2;Ten}Else if(PHead2 = =NULL ){ One             returnPHead1; A         } -          -ListNode Pmergedhead =NULL; the          -         //Recursive invocation -         if(Phead1.val <phead2.val) { -Pmergedhead =PHead1; +             //The following recursive call itself, the returned value is Pmergedhead after the node, until the end of recursion, will return Pmergedhead new head node.  -Pmergedhead.next =merge (Phead1.next, pHead2);  +}Else{ APmergedhead =pHead2; atPmergedhead.next =merge (PHead1, phead2.next); -         } -          -         returnPmergedhead;  -     } -      in      Public Static voidMain (string[] args) { -ListNode Head1 =NewListNode (1); toListNode N1 =NewListNode (3); +ListNode N2 =NewListNode (5); -ListNode n3 =NewListNode (7); theListNode N4 =NewListNode (9); *          $Head1.next =N1;Panax NotoginsengN1.next =N2; -N2.next =N3; theN3.next =N4; +          AListNode head2 =NewListNode (2); theListNode N5 =NewListNode (4); +ListNode N6 =NewListNode (6); -          $Head2.next =N5; $N5.next =N6; -          -Mergesortedlists merge =Newmergesortedlists (); the      -ListNode Mergehead =Merge.merge (Head1, head2);Wuyi          the listnode.printlist (Mergehead);  -          Wu     } -}

Interview question 17: Merge two sorted lists