stdptr

ProgrammingLinkedListsMotivationA"List"isausefulstructuretoholdacollectionofdata.
Currently,weusearraysforlistsExamples:ListoftenstudentsmarksintstudentMarks[10];Listoftemperaturesforthelasttwoweeksdoubletemperature[14];MotivationlistusingstaticarrayintmyArray[10];Wehavetodecideinadvancethesizeofthearray(list)listusingdynamicarrayintn,*myArray;cin>>n;myArray=newint[n];Weallocateanarray(list)ofanyspecifiedsizewhiletheprogramisrunninglinked-list(dynamicsize)size=Thelistisdynamic.
Itcangrowandshrinktoanysize.
LinkedLists:BasicIdeaAlinkedlistisanorderedcollectionofdataEachelementofthelinkedlisthasSomedataAlinktothenextelementThelinkisusedtochainthedataExample:Alinkedlistofintegers:20457585DataLinkThelistcangrowandshrinkLinkedLists:BasicIdeas204575852045add(75),add(85)delete(85),delete(45),delete(20)75Originallinkedlistofintegers:Insertion:DeletionLinkedLists:Operations20457585204575852045758560oldvaluedeleteditem#includeusingnamespacestd;structNode{intdata;Node*next;};typedefNode*NodePtr;typedeftypedefallowsyoutomakenewshortcutstoexistingtypestypedefintWAH;WAHk;//sameas:intk;typedefint*WAHPTR;WAHPTRp;//sameas:int*p;typedefNode*NodePtr;NodePtrHead;//sameas:Node*Head;LinkedListStructureNode:Data+LinkDefinitionstructNode{intdata;//containsusefulinformationNode*next;//pointstonextelementorNULL};CreateaNodeNode*p;p=newNode;//pointstonewlyallocatedmemoryDeleteaNodedeletep;LinkedListStructuresAccessfieldsinanode(*p).
data;//accessthedatafield(*p).
next;//accessthepointerfieldOritcanbeaccessedthiswayp->data//accessthedatafieldp->next//accessthepointerfieldRepresentingandaccessingLinkedListsWedefineapointerNodePtrHead;thatpointstothefirstnodeofthelinkedlist.
WhenthelinkedlistisemptythenHeadisNULL.
20457585HeadPassingaLinkedListtoaFunctionWhenpassingalinkedlisttoafunctionitshouldsufficetopassthevalueofHead.
UsingthevalueofHeadthefunctioncanaccesstheentirelist.
Problem:Ifafunctionchangesthebeginningofalistbyinsertingordeletinganode,thenHeadwillnolongerpointtothebeginningofthelist.
Solution:WhenpassingHeadalwayspassitbyreference(orusingafunctiontoreturnanewpointervalue)20457585HeadManipulationofaUnsortedLinkedListStartthefirstnodefromscratchNodePtrnewPtr;newPtr=newNode;newPtr->data=20;newPtr->next=NULL;Head=newPtr;HeadnewPtr20HeadHead=NULL;InsertingaNodeattheBeginningnewPtr=newNode;newPtr->data=13;newPtr->next=Head;Head=newPtr;HeadnewPtr1320Keepgoing…HeadnewPtr50401320voidaddHead(NodePtr&Head,intnewdata){NodePtrnewPtr=newNode;newPtr->data=newdata;newPtr->next=Head;Head=newPtr;}Addinganelementtothehead:(todelete)DeletingtheHeadNodeNodePtrcur;cur=Head;Head=Head->next;deletecur;Headcur50401320voiddelHead(NodePtr&Head){if(Head!
=NULL){NodePtrcur=Head;Head=Head->next;deletecur;}}DisplayingaLinkedListcur=Head;cur=cur->next;2045Headcur2045HeadcurAlinkedlistisdisplayedbywalkingthroughitsnodesonebyone,anddisplayingtheirdatafields.
voidDisplayList(NodePtrHead){NodePtrcur;cur=Head;while(cur!
=NULL){coutdatanext;}}//returnthepointerofthenodehasdata=item//returnNULLifitemdoesnotexistNodePtrsearchNode(NodePtrHead,intitem){NodePtrCur=Head;NodePtrResult=NULL;while(Cur!
=NULL){if(Cur->data==item)Result=Cur;Cur=Cur->next;}returnResult;}SearchingforanodeOriginallinkedlistofintegers:Addtotheend(insertattheend):Moreoperation:addingtotheend504013205040132060LastelementThekeyishowtolocatethelastelementornodeofthelist!
voidaddEnd(NodePtr&Head,intnewdata){NodePtrlast=Head;NodePtrnewPtr=newNode;newPtr->data=newdata;newPtr->next=NULL;if(Head!
=NULL){//non-emptylistcasewhile(last->next!
=NULL)last=last->next;last->next=newPtr;}else//dealwiththecaseofemptylistHead=newPtr;}Addtotheend:Linknewobjecttolast->nextLinkanewobjecttoemptylistManipulationofaSortedLinkedListInsertingaNodeHeadcur20334575prev.
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newPtrToinsertanewnodeintothelist1.
(a)Createanewnodeusing:NodePtrnewPtr=newnode;(b)Fillinthedatafieldcorrectly.
2.
Find"prev"and"cur"suchthatthenewnodeshouldbeinsertedbetween*prevand*cur.
3.
Connectthenewnodetothelistbyusing:(a)newPtr->next=cur;(b)prev->next=newPtr;FindingprevandcurSupposethatwewanttoinsertordeleteanodewithdatavaluenewValue.
Thenthefollowingcodesuccessfullyfindsprevandcur.
prev=NULL;cur=Head;while(cur!
=NULL&&newValue>cur->data){prev=cur;cur=cur->next;}//insertitemintolinkedlistinascendingordervoidinsertNode(NodePtr&Head,intitem){NodePtrNew,Cur,Pre;New=newNode;New->data=item;Pre=NULL;Cur=Head;while(Cur!
=NULL&&item>Cur->data){Pre=Cur;Cur=Cur->next;}if(Pre==NULL){//inserttoheadoflinkedlistNew->next=Head;Head=New;}else{Pre->next=New;New->next=Cur;}}(todelete)DeletingaNodeTodeleteanodefromthelist1.
Locatethenodetobedeleted(a)curpointstothenode.
(b)prevpointstoitspredecessor2.
Disconnectnodefromlistusing:prev->next=cur->next;3.
Returndeletednodetosystem:deletecur;Headcur20457585prev.
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voiddeleteNode(NodePtr&Head,intitem){NodePtrprev,cur=Head;while(cur!
=NULL&&item>cur->data){prev=cur;cur=cur->next;}if(cur==NULL||cur->data!
=item){coutnext;elseprev->next=cur->next;deletecur;}Deleteanelementinasortedlinkedlist: